(Reuters) - Two people were killed and two critically wounded when a gunman opened fire on two motorists and a Metro bus in Seattle on Wednesday and then caused a collision as he tried to flee in a stolen car during the afternoon rush hour, police said.

The incident unfolded in a northeastern Seattle neighborhood when the suspect approached a motorist at an intersection and shot her before walking into the street and firing on the bus, police said in a statement.

The bus driver, identified by the Seattle Times newspaper and other media as Eric Stark, 53, was shot but managed to turn the bus around and head away from the assailant, police said. The suspect then approached a second motorist in a Toyota Prius and opened fire, killing the driver.

The gunman climbed into the Prius as police arrived and sped away but collided with a nearby vehicle, killing that driver. Officers pursuing the suspect took him into custody after a brief standoff, police said.

Authorities did not immediately offer an explanation for what might have precipitated the shooting or specify the type of weapon used.

“We only believe that this is a one, lone suspect involved in this random, senseless act”, said Seattle Deputy Police Chief Marc Garth Green, according to NBC News. “We’re outraged at what this suspect did.”

The unidentified suspect was taken to a Seattle hospital, where he remained under guard while being treated for injuries that were not life-threatening, according to police.

Police said one motorist was killed by gunfire and the other motorist was killed in the collision. Both were men. None of the victims was immediately identified by police.

The Times reported late on Wednesday that the gunman was a 33-year-old Seattle resident. The man who was fatally shot was 50 and the man who was killed in the collision was 70, it said.

King County’s Metro transit authority said on Twitter the bus driver had activated an emergency alarm to report being shot, and that none of his 12 passengers was injured.

Although wounded in the torso, the bus driver was able to walk to a gurney to be transported by paramedics to hospital, the Seattle Times quoted a transit union president as saying.