A violent attack early Wednesday on a homeless man sleeping in a highly populated area of downtown San Diego is the latest in a series of random attacks that left two men dead and two hospitalized in critical condition, San Diego Police Department (SDPD) officials confirmed.

The attacks, described as "senseless" and random by homicide investigators, have renewed efforts to identify a "person of interest" sought following the killing of a homeless man Sunday.

SDPD is distributing flyers with images of the man considered extremely dangerous, Capt. David Nisleit told reporters Wednesday.

"This is a person we need to have removed from the community as fast as we can," Nisleit said.

A police officer found a man suffering "significant injuries" to his upper torso at State and West E Streets at 5:10 a.m. Wednesday. The location is near condos and the federal courthouse.

Residents told police they were awakened by a loud noise and saw a person crouched over what they thought was clothing. The clothing turned out to be a person.

"The victim had been placed on fire," Nisleit said. "Our witness was able to remove the towel from our victim’s body, saving them from burns."

San Diego Fire-Rescue Department crews responded and treated the victim before transporting him to a nearby hospital.

San Diego Police said the suspect was last seen running north from the area.

SDPD investigators are also following reports of two other incidents reported between 6 and 6:10 a.m.

In one, a man was struck by an unknown object in the back of the head while he was sitting at a bus stop at Fifth Avenue and Washington Street in the Hillcrest area, police said.

Also, a man was hit in the head with a rock while sleeping along Third Avenue west of State Route 163 and near Mercy Hospital, according to police.

Officials have not connected the Hillcrest incidents to the series but Nisleit left no doubt that police were considering the State Street incident the work of the same man who attacked homeless men in the Bay Park and Midway areas.

On Sunday Angelo Di Nardo, 53, was found killed and set on fire along Morena Boulevard, east of Interstate 5, homicide investigators said.

Shawn Longley, 41, was found by police Monday morning on Bacon Street in Ocean Beach. He had suffered blunt force trauma to his upper body and was pronounced dead at the scene.

Manuel Mason, 61, was attacked about an hour earlier on Monday in San Diego's Midway District. He was taken to the hospital with life-threatening injuries.

Nisleit would not divulge what connects these crimes but said, "I can tell you we are absolutely convinced these cases are linked and we will work them as a series."

Homicide investigators want to question a man spotted on store surveillance video near the Morena Boulevard scene. The man purchased a gas can, a gallon of gasoline and a lighter about 15 minutes before De Nardo's body was discovered.

“If you know who this person is, call 911. Do not approach this person, we’re going to consider him extremely dangerous,” Nisleit said.

NBC 7 tracked down the store clerk who sold a man fire supplies just 15 minutes before a fire was reported to police.

The clerk, who wished only to be identified as “Elliott,” said he is haunted by the encounter.

“If I knew what was going to happen, I would, like, examine him but he was just another customer,” Elliott told NBC 7 in an exclusive interview.

Images: Person Sought for Questioning in Homeless Attacks

Anyone with information can call the San Diego Police Department's Homicide Unit at (619) 531-2293 or the Crime Stoppers anonymous tip line at (888) 580-8477. A $1,000 reward is being offered for information leading to an arrest.

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