San Diego’s homeless population had been gripped by terror for much of the last few weeks.

Some took to sleeping with large groups of people. Ruben Azevedo, 27, said he was unwilling to sleep at all at night, and instead walked all over town after dark, and tried to nap in parks during the daytime. He was not able to get a bed at a shelter, he said. (The city’s largest shelters are almost always at or above capacity.)

“It disturbed me,” he said of the killings. “I don’t want someone to pour fuel on me.”

But homeless advocates have warned that one arrest would hardly end the violence against homeless people, who have become targets of hate crimes and other violence as their ranks have grown in cities like San Diego. Between 1999 and 2015, more than 400 homeless people were killed nationwide by people who were not homeless, while many more were raped, beaten and mutilated, according to a survey conducted by the National Coalition for the Homeless.

The San Diego killings are the second time in four years that a serial killer has targeted the homeless in Southern California. Itzcoatl Ocampo was charged with killing six people, including four homeless men in Orange County in 2012.

“We can’t all rest easier,” said Michael McConnell, an advocate for the homeless in San Diego. “People on the street still have the same challenges they did before this killer struck. They still have to deal wit the same high level of violence.”