Six people were injured Thursday morning in San Francisco when the 21 Muni bus crashed into a yellow Twin Cities trolley at the intersection of 6th and Market streets, officials said.

Firefighters responded to the accident at 10:10 a.m., said Lt. Jonathan Baxter, a spokesman for the San Francisco Fire Department. Two people were reportedly taken to the hospital.

None of the injuries are considered life threatening.

Chenyu Wang, a San Francisco resident, was sitting in a coffee shop across the street at the time of the accident.

“I heard the noise and it didn’t sound that bad — then a stretcher came out,” he said.

Wang said he didn’t see anyone transported on the stretcher, but he saw people talking to paramedics. After the crash, people filed out of the two vehicles.

The collision cracked the front windshield of the bus.

Paul Rose, a spokesman for San Francisco Municipal Transportation Agency, said that the bus rear-ended the trolley, which is one of the historic vehicles that Muni purchased in 2010. It was originally used in St. Paul and Minneapolis in the 1940s.

Christine Hong, another witness, called the accident “a big deal” because it involved two city-owned vehicles.

Around 11:20 a.m. both vehicles had been removed from the scene.