San Diego Authorities Search for Killer Accused of Beating and Setting Homeless People on Fire

— -- Authorities in San Diego, California, are currently trying to catch a killer believed to be preying on the city's homeless population.

The suspect, who has not been identified and remains at large, is believed to be responsible for four violent attacks in the city this past week, according to the San Diego Police Department (SDPD). The victims, all homeless people, were sleeping when they were targeted by the suspect, police said.

In two of the incidents, the victims were "lit on fire," the SDPD said in a news release on Wednesday. The brutal attacks have left two dead and two others with life-threatening injuries. One of the survivors is not expected to live.

"These evil acts of violence are some of the worst that I’ve seen in my 34 years in law enforcement," San Diego Police Chief Shelley Zimmerman said at a news conference on Wednesday.

"This killer has targeted some of our community’s most vulnerable citizens while they are asleep," she added. "I want everyone to know that this series against our homeless is the highest priority for our police department."

Investigators are offering a $1,000 reward for information leading to the arrest of the suspect, whom police believe was caught on a convenience store's security camera.

"There is no doubt in our minds that this person depicted on these photos and depicted on these videos is the person responsible," SDPD Capt. David Nieslit said at the news conference. "I cannot go into detail why we say that, but we’re quite confident this is the same person responsible for all."

San Diego Mayor Kevin Faulconer called the attacks against the city's homeless "absolutely reprehensible."

"SDPD is bringing all its resources to bear to find the person responsible and seek justice for the victims," he said in a statement on Twitter on Wednesday. "Police officers are also conducting extensive community outreach to provide information to homeless individuals to keep them safe."

As the suspected killer is still on the loose, authorities said they have been urging local homeless people to remain vigilant, to avoid sleeping alone and to stay in open, well-lit areas.

One homeless man in the city told ABC affiliate KGTV that he and his friends "came up with an idea of actually sleeping in shifts."

"Every time I speak about it and every time I talk about it, it sends chills through my spine," the man, who wished not to be identified, said of the recent string of attacks.