(Reuters) - A Seattle man accused of killing two people and seriously wounding two more while firing into rush hour traffic will be formally charged in court on Friday, though police have uncovered no motive for the shooting spree.

Tad Michael Norman, 33, is being held without bond at the King County jail under investigation for charges of homicide, robbery and assault, jail records show.

Wednesday’s shootings were “a random and senseless act”, the city’s deputy police chief, Marc Garth Green, told a media briefing.

Norman is expected to appear before a judge on Friday morning, but it was not immediately clear if he had an attorney.

Media said Norman appeared intoxicated when he walked into traffic in the northeastern neighborhood of Sand Point at about 4 p.m. on Wednesday and began shooting.

Norman is accused of having approached a motorist at an intersection and shooting her before walking into the street and firing on the bus, police said.

He shot through the bus’s windshield, wounding the driver, Eric Stark, 53, who then quickly turned the bus around drove away to protect his 12 passengers, officials said.

Stark, wounded in the torso, was hailed a hero by Seattle’s mayor, police chief and others for his quick response.

The suspect then approached another motorist in a red Toyota Prius and opened fire, killing the driver, identified by the Seattle Times and other media as Robert Hassan, 76, a physician and retired colonel in the Air Force.

Then, in Hassan’s car, Norman allegedly led police on a short chase before he collided with another car, killing its driver, 75-year-old Richard Lee, the Times said.

He was arrested and taken to a hospital to be treated for minor injuries before going to jail.

The first person shot, identified by media as second-grade school teacher Ashley Judd, 56, is recovering in hospital along with Stark.

Judd appeared on television on Thursday to reassure students about her condition. “I’ll be back, I love them,” she said during a bedside news conference.

Of the gunman, she said, “He walked straight in the middle of the road and just pointed a gun at me and just shot at me.”