[Update 11:55 p.m.]

(CNN) -- The gunman who went on a shooting rampage in Santa Monica, California, killed four people, police spokesman St. Richard Lewis said. Authorities said earlier that six had died, but revised the number to four. The gunman was also killed, bringing the total number of deaths to five.

The shooter began his rampage at a residence near the campus of Santa Monica College, opening fire in a house, where police later found two bodies. He then shot at a passing car before carjacking another vehicle, Lewis said. He forced the driver, a woman, to drive onto the college campus. There he shot two people in a passing vehicle. One died at the scene. The gunman also fatally shot someone outside the campus library, where he engaged police in a gunfight, Lewis said. Officers fatally wounded him.

[Earlier story]

(CNN) -- Six people were killed in a shooting rampage in Santa Monica, California, that ended Friday with the gunman clad in tactical gear dead in a college library and a "person of interest" in custody, authorities said.

"We are not convinced 100 percent that the suspect who was killed operated in a solo or alone capacity," Santa Monica Police Chief Jacqueline Seabrooks told reporters.

The comments came as police and firefighters searched the sprawling campus of Santa Monica College for other possible victims or shooters. By early evening, authorities declared the campus clear.

The gunman has not been identified by authorities, Seabrooks said. She described him as a white male between the age of 25 and 35, clad in black and wearing what appeared to be a ballistic vest. He carried a semi-automatic assault rifle, she said.

Seabrooks did not identify the person in custody, nor did she explain why authorities wanted to talk with the individual.

At least three people were wounded in the shootings, which authorities believe began with a house fire and gunshots shortly before noon in a residential neighborhood near the college.

Jerry Cunningham was home when she heard the shots, and stepped out onto her porch to see what happened.

She saw the gunman firing at a neighboring house, and then she noticed it was on fire. She saw the gunman carjack a vehicle.

As he was holding the female motorist at gunpoint, the gunman waved another car by, Cunningham said. That driver, also a woman, hesitated for just a moment, and the gunman "fired three shots directly into her and the car," Cunningham said. The motorist was wounded in the shoulder, she said.

Inside the house, firefighters found the bodies of at least two people, Seabrooks said.

Map: Shooting in Santa Monica

Investigators believe the gunman knew the dead people in the house, but police were unsure of the connection.

The others killed in the rampage were targeted randomly, Seabrooks said.

Investigators did not immediately identify the victims, saying authorities were still making next-of-kin notifications.

It was not immediately clear whether a woman who died from wounds at Ronald Reagan UCLA Medical Center was counted among the six deaths. Another woman wounded in the shooting remains in critical condition, Dr. Marshall Morgan, chief of emergency medicine at the medical center, said Friday evening.

Within minutes of the carjacking, authorities said, the gunman targeted a bus in Santa Monica. Two passengers were injured, Suja Lowenthal, a Big Blue Bus spokeswoman, told CNN.

A short distance later, the gunman opened fire on cars, including a patrol car, adjacent to the college.

"There was an exchange of gunfire at the time, and the suspect tried to evade," Seabrooks said.

The gunman ran on to the campus, where he again exchanged gunfire with police.

Student Joe Orcutt saw the exchange of gunfire and fled, only to come face-to-face later with the gunman near the campus parking lot.

"He was standing there. He looked over at me, and I looked at him. He just panned his gun and trained it on me, and I just jumped behind the building and he shot at me," Orcutt said.

Orcutt said he heard bullets "whiz by my head."

The gunman was "very calm, not running around." He was just "looking around for targets very casually," he said.

"He just looked like he was standing there posing for the cover an ammo magazine or something. It was bizarre."

The gunman exchanged gunfire at least once on the campus with police, Seabrooks said.

As he fled toward the campus library, he shot a woman, she said.

A number of students were in the library building studying for finals when the gunman burst in. More than 30,000 students are enrolled in the two-year community college.

A woman -- who was shaken up by the ordeal and asked not to be identified -- said she was in the building when she heard a noise, realized it was a gunshot, then took off running.

Then, in a hallway, she saw a dark-haired man whom she initially mistook for a police officer but later realized was the shooter. The man -- who she said was wearing black combat boots and what appeared to be a bullet-proof vest -- was quiet and walking casually.

"(He had) a big shotgun," the woman said.

She and a colleague eventually realized something wasn't right and ran in the opposite direction. "Multiple" gunshots rang out at one point, in an exchange of gunfire the woman described as like a war zone.

Priscilla Morales, who was also studying in the library, told CNN she looked out the window and saw people running.

She and her friends grabbed their books and belongings to leave the study room. "As we open the door, we hear three gunshots," she said.

Morales and the others closed the door and hid.

Still, she could hear the commotion: gunshots and then the gunman screaming.

Morales also said she heard police tell the gunman to "drop it."

"I was so scared and thought literally I was going to die," she said.

President Barack Obama was in Santa Monica for a fundraiser just a 10-minute drive from the campus, CNN affiliate KCAL/KCBS reported. Obama's schedule was not affected by the shootings or police followup.