Seeking to track down some of the 40 to 60 teen robbers who took over a train car in Oakland, BART police investigators have pored over video footage, interviewed witnesses, combed through social media chatter and shared surveillance images of the suspects with other police agencies in an all-points bulletin.

But the one thing the transit agency didn’t do in the immediate aftermath of the mob robbery is announce what had happened to riders and other members of the public — and seek to enlist their help.

The shocking crime occurred at 9:30 p.m. Saturday when a crowd of juveniles swept into the Coliseum/Oakland Airport Station, hurdling fare gates and racing to the second-story platform, where they rushed onto a train, forcing passengers in at least one car to hand over their phones and other valuables and bloodying at least two riders.

The robbers fled and scattered before two police officers who had been patrolling a rear parking lot at the station arrived minutes later.

BART communicates with its riders and the public at large in a number of ways, including a website, an app, email alerts, a Facebook account and Twitter feeds. But officials did not use those tools to notify the public until after The Chronicle received a tip about the crime on Monday morning. Even riders who were on the same train as the robbery victims but on different cars weren’t alerted as to why the train was stopped for so long.

Back to Gallery BART keeps riders in dark about teen mob robbery 2 1 of 2 Photo: Noah Berger, Special to The Chronicle 2 of 2 Photo: Noah Berger / Special to The Chronicle



Alyssa Hammonds, who lives in Pleasanton and said she was on a different car on the train in question, said she heard the train operator say something was going on and saw a couple of people who looked “shaken” but was otherwise left in the dark.

“We didn’t know what was happening until” Monday, Hammonds said.

A BART spokeswoman, Alicia Trost, said a summary of the crime appeared Sunday morning in a daily police log available to the media by email.

Tony Ribera, a former San Francisco police chief who directs the International Institute of Criminal Justice Leadership at the University of San Francisco, said he didn’t understand why BART didn’t publicize the crime sooner — both to enhance public safety and to enlist help in finding the offenders.

“It seems to me rather strange ... but maybe they had other reasons,” Ribera said. “Usually, the quicker you get information out, the more likely you’re going to solve the case. The longer you wait, the less likely that is to happen.”

Ribera said making the crime public can be critical for locating witnesses and identifying those involved. And releasing surveillance photos and videos, he said, is often key to the effort.

BART faces a separate set of issues related to surveillance images of the suspects. Officials declined Tuesday to release images from cameras at Coliseum Station, citing a policy of protecting the identity of juveniles, but did send them confidentially to outside police agencies in a bulletin known as a BOLO, which stands for “be on the lookout.”

“The video clearly shows that these were young kids and young teens,” said Trost, whose agency has boosted the number of officers patrolling Oakland stations in response to Saturday’s robbery and an overall rise in police calls.

David Snyder, an attorney and the executive director at the First Amendment Coalition in San Rafael, said such a policy made sense because California law offers special protections for minors accused of a crime. However, Snyder said that doesn’t mean the agency can’t release images or video with the identifying features of juveniles redacted — for instance, with their faces blurred — which BART officials have done in the past.

“They may be being overly cautious,” Snyder said.

BART has faced questions in the past about delays between crimes and the agency’s release of information to the public.

After a 19-year-old man was shot to death on a train car as it moved through Oakland in January 2016, BART circulated clear surveillance images it captured of the suspect to other law enforcement agencies, but it waited four days to release them to the public, after The Chronicle had obtained them.

Then-Police Chief Kenton Rainey said at the time that investigators didn’t want to influence witness descriptions of the suspect, who fled from the West Oakland Station.

In the same case, BART waited nine days to reveal that the suspect and the victim had an earlier, video-recorded encounter on a bus ride from Antioch to the Pittsburg/Bay Point Station. After The Chronicle learned of the bus ride, BART officials confirmed it, while explaining they had not wanted to tip off the suspect that investigators knew he had been on the bus.

The killer remains at large.

Michael Cabanatuan and Kurtis Alexander are San Francisco Chronicle staff writers. Email: mcabanatuan@sfchronicle.com, kalexander@sfchronicle.com Twitter: @ctuan @kurtisalexander