A violent night in Oakland claimed the lives of two men early Sunday morning and had authorities searching for a gunman who opened fire on an Oakland police officer late Saturday in East Oakland, officials said.

A police supervisor, who was not named, was responding to a call on the 1900 block of 73rd Street around 9:30 p.m. Saturday when she was involved in a collision, said Officer Johnna Watson, an Oakland police spokeswoman.

Shortly after the crash, a gunman approached the officer, opened fire on her patrol sport utility vehicle, and fled. The officer was not struck but was taken to Highland Hospital with unspecified injuries after the crash, Watson said.

The officer was alert and recovering Sunday morning, police said.

Officers from multiple agencies continue to scour the area around the shooting, about 1½ miles from Oracle Arena.

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Authorities have not released any information about the gunman.

In apparently unrelated incidents, two men were killed in shootings. The first took place at 1:15 a.m. in the 9200 block of Holly Street. Eight minutes later, in the 1000 block of Seventh Street, another man was shot and killed. No suspects have been taken into custody, Officer Nicole Allen said, and the names of the victims have not been released.

Saturday’s attack on the supervisor came as police around the country are on high alert after two ambush-style executions of officers.

Three officers were shot dead and three others were wounded July 17 as they responded to a call about a man with a gun in Baton Rouge, La.

On July 7, a gunman saying he was seeking revenge for two recent high-profile police killings of black men shot and killed five police officers during a peaceful Black Lives Matter protest in Dallas.

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Since the Dallas attack, Oakland officers have been assigned partners while on patrol. The officer attacked Saturday was driving alone because she is a supervisor, police said.

Evan Sernoffsky and Michael Cabanatuan are San Francisco Chronicle staff writers. Email: esernoffsky@sfchronicle.com, mcabanatuan@sfchronicle.com Twitter: @EvanSernoffsky, @ctuan