(AP) -- First was the killing of a Muslim man from Afghanistan late last year. Then came two more slayings in the last two weeks -- men from Pakistan who attended the same mosque in Albuquerque, New Mexico.
Those deaths were followed Friday by the city's fourth homicide of a Muslim man in nine months. Together the killings have sent ripples of fear through Islamic communities in New Mexico and beyond and fueled a race to find who was responsible.
Authorities on Monday identified the latest victim as they sought help searching for a vehicle believed to be connected to the slayings. The common elements were the victims' race and religion, officials said.
Naeem Hussain was killed Friday night, and the three other men died in ambush shootings. Police in New Mexico's largest city are trying to determine if the deaths are linked.
"The fact the suspect remains at large is terrifying," Debbie Almontaser, a Muslim community leader in New York, wrote on Twitter. "Who is next?!"
In a phone interview, Almontaser said that a female friend who lives in Michigan and wears the hijab head covering shared with her over the weekend just how rattled she was. "She's like, 'This is so terrifying. I'm so scared. I travel alone,'" Almontaser said.
Hussain, 25, was from Pakistan. His death came just days after those of Muhammad Afzaal Hussain, 27, and Aftab Hussein, 41, who were also from Pakistan and members of the same mosque.
The earliest case involves the November killing of Mohammad Ahmadi, 62, from Afghanistan.
Aneela Abad, general secretary at the Islamic Center of New Mexico, described a community reeling from the killings, its grief compounded by confusion and fear of what may follow.
"We are just completely shocked and still trying to comprehend and understand what happened, how and why," she said.
Some people have avoided going out unless "absolutely necessary," and some Muslim university students have been wondering whether it is safe for them to stay in the city, she said. The center has also beefed up its security.
Police said the same vehicle is suspected of being used in all four homicides -- a dark gray or silver four-door Volkswagen that appears to be a Jetta or Passat with dark tinted windows. Authorities released photos hoping people could help identify the car and offered a $20,000 reward for information leading to an arrest.
Investigators did not say where the images were taken or what led them to suspect the car was involved in the slayings. Police spokesperson Gilbert Gallegos said in an email Monday that the agency has received tips regarding the car but did not elaborate.
"We have a very, very strong link," Albuquerque Mayor Tim Keller said Sunday. "We have a vehicle of interest … We have got to find this vehicle."
Gallegos said he could not comment on what kind of gun was used in the shootings, or whether police know how many suspects were involved in the violence.
President Joe Biden said he was "angered and saddened" by the killings and that his administration "stands strongly with the Muslim community."
"These hateful attacks have no place in America," Biden said Sunday in a tweet.
The conversation about safety has also dominated WhatsApp and email groups that Almontaser is on.
"What we've seen happen in New Mexico is very chilling for us as a Muslim minority community in the United States that has endured so much backlash and discrimination" since the 9/11 attacks, she said. "It's frightening."
Few anti-Muslim hate crimes have been recorded in Albuquerque over the last five years, according to FBI data cited by Brian Levin, director of the Center for the Study of Hate and Extremism and a professor of criminal justice at California State University at San Bernardino.
From 2017 through 2020, there was one anti-Muslim hate crime a year. The highest recent number was in 2016, when Albuquerque police recorded six out of a total of 25 hate crimes.
That largely tracks with national trends, which hit the lowest numbers in a decade in 2020, only to increase by 45% in 2021 in a dozen cities and states, Levin said.
Albuquerque authorities say they cannot determine if the slayings were hate crimes until they have identified a suspect and a motive.
Louis Schlesinger, a forensic psychology professor at John Jay College of Criminal Justice in New York, said bias killings are often perpetrated by a small group of people, typically young white men. A lone perpetrator is rare.
"These are basically total losers by every dimension, whether it's social, economic, psychological, what have you," he said. "They're filled with hatred for one reason or another and target a particular group that they see, in their mind, to blame for all their problems in life."
It was not clear whether the victims knew their attacker or attackers.
The most recent victim was found dead after police received a call of a shooting. Authorities declined to say whether the killing was carried out in a way similar to the other deaths.
Muhammad Afzaal Hussain had worked as a field organizer for a local congresswoman's campaign.
Democratic Rep. Melanie Stansbury issued a statement praising him as "one of the kindest and hardest working people" she has ever known. She said the urban planner was "committed to making our public spaces work for every person and cleaning up legacy pollution."
As land-use director for the city of Española -- more than 85 miles (137 kilometers) north of Albuquerque -- Hussain worked to improve conditions and inclusivity for disadvantaged minorities, the mayor's office said.