OAKLAND — A pair of unidentified Good Samaritans’ swift response led to a 32-year-old San Francisco man’s arrest on suspicion of attempted murder after the weekend stabbing of multiple people inside the Coliseum BART station, authorities said.

On Saturday afternoon, two victims, identified only as a woman in her 60s and her brother, a man in his 50s, boarded a train at the system’s South San Francisco station, BART spokeswoman Alicia Trost said in a statement Sunday.

The suspect, identified as Robert Dolph, boarded at the Civic Center/UN Plaza Station, and was acting erratically with verbal outbursts.

At 2:52 p.m. Saturday, when the woman and man got off their train car at Coliseum, Dolph followed them toward the station fare gates. There, Dolph pulled out a knife and began attacking the pair without provocation, Trost said.

As a station agent called police, a Good Samaritan managed to grab the knife away from Dolph and hold him down, while a second Good Samaritan joined in until BART police arrived within two minutes.

A third victim suffered superficial wounds and was treated at the scene, BART spokeswoman Anna Duckworth said.

An ambulance also responded, taking the woman and her brother to a hospital where she was listed in fair condition and he was in critical but stable condition Sunday.

Officers, who said Dolph admitted his actions in an interview with investigators, recovered a knife at the scene.

Dolph was booked him into Santa Rita Jail in Dublin on suspicion of attempted murder. He faces a 9 a.m.Tuesday arraignment at Oakland’s Wiley Manuel courthouse.

The Coliseum Station and Oakland Airport Connector were shut down for about two hours for investigators’ response, just as many riders began heading to Oracle Arena for a 5:30 p.m. Golden State Warriors game.