About 100 people were evacuated and traffic on two busy San Francisco thoroughfares was rerouted Monday as police disabled a homemade bomb in the restroom of a Starbucks coffee shop.

An employee saw what appeared to be a suspicious device on the floor of the unisex bathroom at the Starbucks at Van Ness Avenue and Bush Street around 1:15 p.m. and called police, Sgt. Neville Gittens said.

Gittens would not describe the bomb or its size other than to say it “would have caused damage if it exploded.”

Don Henschke, sales manager at Ellis Brooks Auto Center across the street from the coffeehouse, said a police officer described the bomb to him as “a portion of a flashlight and a fuse.”

Mamoru Ogawa said police called the device a pipe bomb as they evacuated him, his wife and two customers from the sushi restaurant that he owns next door to the building that houses the Starbucks.

The bomb squad disabled the device at about 2:10 p.m., and witnesses said they heard a popping sound at the time.

Gittens said no one phoned in a bomb threat or took responsibility for the device, but he said investigators have a “pretty good lead” on a suspect.

Traffic on Van Ness between Sutter and Pine streets, and on Bush between Franklin and Polk streets was rerouted from about 1:30 to 2:30 p.m. People were evacuated from the Starbucks, a seven-story apartment building above the coffee house and Ogawa’s restaurant.

Vandals have targeted San Francisco Starbucks in the past.