A pickup truck with the two suspects was stopped at South Van Ness Avenue and 15th Street. The apparent pipe bomb explosion happened near a home at Newhall and Lasalle Streets.
There are still some glass markings on the street from the explosion on Newhall Street. Nobody was hurt. And thanks to many tips, police were able to arrest two suspects.
This wasn't your ordinary traffic stop in SF's Mission District. Heidi Erbe said the loud sounds of the police talking on a bullhorn jolted her awake.
"There were so many cop cars out, all the cops were sort of perched behind the cars with their doors open and their guns out, and then they basically just told the passenger to get out the driver side door and he came out with his hands up," said Erbe.
Police took two men in their 20s in for questioning because their truck was seen leaving the Bayview neighborhood where a pipeline exploded on the street early Friday morning.
"A little after 5:00 am this morning we received various calls of shots being fired or an explosion that occurred on the 1100 block of Lasalle," said Sgt. Neville Gittens, San Francisco police department.
On Lasalle and Newhall Streets officers found evidence of a pipe-bomb; a piece was still lodged in the side of a residential building. No one was hurt in the explosion, but police were concerned that the truck spotted at the scene was carrying explosive materials.
"We have our bomb squad here going through procedures - to number one find out if there are any additional explosives in the vehicle," said Sgt. Gittens.
While the bomb squad searched the vehicle for explosives, a portion of South Van Ness Avenue between 14th and 16th Streets was shutdown to traffic until investigators cleared the truck of all evidence. Residents closest to it were asked to shelter-in-place.
"If they really thought there were pipe-bombs in the truck - I'm surprised they didn't evacuate the houses all around," said Erbe.
San Francisco police say the two men are still being questioned. There is no known motive, but the incident did raise some questions about whether there were any connections about a pipe bombing that took place in San Jose last month outside of a Mongols motorcycle member's house. This happened after a member of the Mongols was accused of fatally shooting the head of a San Francisco's Hells Angels chapter. The police said there is "no connection at this time."