"I see from the window, this is the place where my brother died," said Hussain, who lived in the same Albuquerque apartment complex as his brother Muhammad Afzaal Hussain.

"I'm scared to go outside of my apartment," the grieving brother said. "I'm scared to sit on my balcony."

For Muslims in New Mexico, everyday life is now permeated by fear after four Muslim men --- including Muhammad Afzaal Hussain -- were gunned down in Albuquerque.

Three of the victims -- Hussain, 27; Aftab Hussein, 41, and Mohammad Ahmadi, 62 -- were all "ambushed with no warning, fired on and killed," said Kyle Hartsock, deputy commander of Albuquerque Police Department's Criminal Investigations Division.

Naeem Hussain, 25, died hours after attending a funeral for two other shooting victims.

The fourth victim -- 25-year-old Naeem Hussain -- was found dead Friday night by Albuquerque police. He became the third Muslim man killed in the city within two weeks and the fourth since November.

Hours before his death, Naeem Hussain -- who just became a US citizen -- attended a funeral for two of the other shooting victims. The young man expressed concern about the recent shootings, said Tahir Gauba, spokesperson for the Islamic Center of New Mexico.

While no suspect information has been released, Albuquerque police say the killings of the four men from South Asia "may be connected."

Hussain said whoever killed his brother didn't just steal the life of a beloved family member; they also ripped away his family's sense of freedom.

"My kids do not allow me even to step out of my apartment. They say, 'Dad, it's scary,'" Hussain said just steps from where his brother was gunned down.

"We planted some flowers in our yard, and we haven't even watered them. They said, 'No, somebody might be hiding over there.'"

Hussain had the grim task of identifying his brother's remains at the medical examiner's office. He said his brother's body was mutilated so badly, it was clear the killing was deliberate.

"More than half of his head is gone. ... At the time that I saw the body, he didn't even have half of the face," Hussain said.

"This is not a random killing. This is extremely motivated and extreme hatred."

Reward money increases, but so does the anxiety

The grief and terror have spread to Muslims across New Mexico, said Ahmad Assed, president of the Islamic Center of New Mexico.

"Incredibly terrified. Panicked. Some people want to move from the state until this thing is over. Some people have moved from the state," Assed said.

"Businesses are closing ... early. Students won't leave their homes," he said. "It's affecting people from coming over to the mosque to conduct their services, their prayers."

Police are seeking "a vehicle of interest" that might be connected to the four killings. They tweeted a photo of the car, a dark gray or silver Volkswagen with four doors and tinted windows. Police said it might be a Volkswagen Jetta.

Anyone with information about the car or about the killings is asked to call the FBI at 1-800-CALL-FBI or contact Crime Stoppers at 505-843-STOP or CrimeStoppersNM.com.

"All information you provide will be anonymous and confidential," the city of Albuquerque said. "There is a $20,000 reward from Crime Stoppers and a $10,000 reward from Council on American-Islamic Relations for information that leads to an arrest."

Hussain said his family is fearful of going out with a killer or killers on the loose. But he said he's speaking out to try to stop the violence.

"I am raising voice for my brother because I do not want any other's brother to become victim of those shooters, any sister to become victim of those shooters, any mom or dad to become victim of shooter," Hussain said.

He said he hopes "other people do not become victim of those shooters and suffer like I'm suffering."

'They are afraid to go to school'

While police have not called the four killings hate crimes, "in my opinion, clearly it is hate-driven," Albuquerque Mayor Tim Keller said Monday.

"They are obviously targeting Muslim men, and they are happening right here in our own refugee community," Keller told CNN.

"We know that folks in our community, in the Muslim community especially, they are afraid to even leave their house, especially at night. They are afraid to pray. They are afraid to go to school," the mayor said.

Albuquerque is not just "in a place of grieving right now, but also at a place of outrage," Keller said. But the community is determined to help.

"We have marshaled every resource to have now police presence at all our mosques during prayer time," the mayor said. "We are even doing meal deliveries for families that are afraid to leave their house to get food."

Assed, the mosque president, said he's now among the many Muslims in New Mexico grappling with fear every day.

"I get in the car, and I'm watching every which way possible. I'm watching my side mirror. I'm looking in the back. I'm looking out for any sign of anything out of the ordinary," he said.

"At the end of the day, we don't have an alternative."

A new US citizen who fled religious persecution is killed in America

Naeem Hussain migrated as a refugee from Pakistan in 2016 -- fleeing persecution as a Shia Muslim -- and had become a US citizen just last month, according to his brother-in-law, Ehsan Shahalami.

"He was the most generous, kind, giving, patient and down-to-earth person that I could ever meet," said Shahalami. "He was very hardworking. He shared whatever he made with his family back home."

The young man, who opened his own trucking business this year, had plans to bring his wife over from Pakistan and buy some property in Virginia, Shahalami said.

"He had a lot of dreams, and he accomplished some of them," Shahalami said. "His others were cut short by this heinous act."

The day he was killed, Hussain attended a funeral for two other Muslim men who were recently killed in the city, said Tahir Gauba, director of public affairs with the Islamic Center of New Mexico.

Hussain went to a lunch at the mosque after the funerals and approached Gauba to ask if he had more information on the shootings, Gauba told CNN.

"He stopped by to say 'Hey, what's going on?' He was worried. I told him to be careful," Gauba said.

"We thought after burial of these two young men (on Friday), we would have closure and move on and let law enforcement investigate," Gauba said. "Waking up Saturday morning to his death, the whole community just feels helpless. There's a lot of fear. ... It's driving everybody crazy."

Two other Muslim men killed -- Muhammed Afzaal Hussain and Aftab Hussein -- were members of the same mosque. Both were from Pakistan and were killed in southeast Albuquerque just days apart, police said.

After their killings, police began investigating whether the November 7 slaying of Mohammad Ahmadi, a Muslim man from Afghanistan, was connected.

'The fear is so strong'

The Islamic Center of New Mexico is painfully familiar with violence against Muslims in the community.

An arsonist started a fire on the center's property in November, the city of Albuquerque's website said. A month later, police arrested someone on suspicion of arson and negligent arson.

Fortunately, no one was in the mosque at the time of the fire, Assed said.

But now the center, where about 700 to 800 Muslims gather on Fridays, is warning residents to be cautious.

"We urge everyone to take precautions and be aware of your surroundings including making sure that you are not being followed home and avoid walking alone at night," the center posted on Facebook. "This is especially true for our members living in the southeast part of the city where these killings have taken place."

After Hussain's killing Friday, New Mexico Gov. Michelle Lujan Grisham announced she will send additional state police to Albuquerque.

The city is also increasing police presence at mosques, Muslim-affiliated schools and the University of New Mexico, officials announced.

"We have heard from the community that the fear is so strong, there is a concern about even things like groceries and getting meals for certain folks in certain areas of town," Keller said in a weekend briefing, adding the city is helping with providing meals for those affected by the killings.

Albuquerque has always felt like a welcoming community for Muslims, even after 9/11, Gauba said. "This is the first time we are feeling this kind of atmosphere," he said. "We are in fear."