Two people were shot and killed and a third was injured at a shopping center in Bend, Ore., on Sunday, prompting law enforcement agencies to flood the area and enter a grocery store, where officers found the gunman dead from a gunshot wound, the authorities said.

Officers were still investigating a motive, and they did not release names of the victims or gunman. Lisa Goodman, a spokeswoman for Saint Charles hospital in Bend, said one injured person had been admitted there and that the individual’s condition was “good.”

The shooting began at about 7 p.m. Pacific Daylight Time at the parking lot of the Forum Shopping Center in Bend, about 160 miles southeast of Portland. The authorities said one witness told them that there may have been a second shooter, but Chief Mike Krantz of the Bend Police Department said in a news conference on Sunday night that officers had “not found any evidence of a second shooter or additional gunfire in the area.”

The gunman began shooting in the parking lot and then entered a Safeway grocery store, where he shot and killed one person near the front door, Sheila Miller, a spokeswoman for the Bend Police Department, said by phone on Sunday.

He continued walking through the store, firing multiple rounds, the police said. The gunman then fatally shot another person inside the store, Ms. Miller said.

When police officers entered the store, they found the gunman dead, as well as an AR-15-style rifle and a shotgun near him, Chief Krantz said. Police officers did not fire at the gunman, he said.

The shooting came a little more than three months after a gunman armed with an assault-style weapon killed 10 people and wounded three others in an attack at a Tops supermarket in Buffalo.

The shooting also underscored how the routine task of grocery shopping has become another place where frightening gun violence can occur. In September last year, a gunman killed one person and injured 14 at a Kroger grocery store in Collierville, Tenn. Earlier that year in March, 10 people were killed in an attack a supermarket in Boulder, Colo.

The Forum Shopping Center is a popular spot for locals, who visit the center for its various stores like Old Navy, Big Lots and Safeway. Lindsey Brunsman, 40, a photographer and personal trainer, said she had been walking her dog in a nearby park around 7 p.m. when she heard several pops.

“I have guns and like to go shooting, and I know what those sound like,” she said. “I thought, ‘I really hope that’s not what I think it is.’”

Jessica Swartz, the owner of River’s Place, a nearby food cart, said she did not hear any gunfire over the sound of music from a live band. But she saw her customers suddenly getting up and leaving in a “mass exodus.”

Ms. Swartz recalled thinking: What is happening?

“I feel like we’ve now become a statistic,” she said.