Police arrested 30-year-old Bobby Brown on Tuesday at 31st and Judah Street in the Sunset District. They say surveillance video from the Muni train, where he attacked a woman on Monday, helped police catch him.
"We are ending tonight this defendant's reign of terror," said San Francisco District Attorney Kamala Harris. "We are going to sleep safer tonight as a community because of the work that has been done."
Harris says Brown was a serial attacker who stabbed four innocent people. All four victims were either walking on the street or riding Muni.
"We don't know why he did what he did, but frankly, we don't necessarily have to prove in a court of law why he did what he did," said Harris.
Police say 11-year-old Hatim Mansouri was the first victim. Hatim was stabbed in the liver and stomach while riding the 49-Mission bus on September 1, 2009. Then on November 14, police say Brown stabbed a 25-year-old woman as she crossed the street at 10 a.m. at Sutter and Jones.
"The suspect approached the woman, asked for change, the woman refused, and the suspect, as the woman crossed the street, ran up behind her and stabbed her in the back," said San Francisco police Cmdr. John Loftus.
On November 26, police say Brown attacked a 26-year-old woman while she was walking near City Hall, at Golden Gate and Leavenworth, with her three children.
Then Monday, police say he stabbed 24-year-old Rachel Haynes-Brown on the J-Church metro line.
"He stabbed me twice in the side right here," said Haynes-Brown.
Police say the suspect used a corkscrew in Rachel's attack. She says he physical wounds are healing, but it will take longer to heal her emotional wounds.
"It's really traumatizing, you know, to be walking down the street and be anxious about everybody walking behind me you know," said Haynes-Brown.
Police are also looking into two other cases of random stabbings in the city and they're asking for the public's help in identifying the suspect.
Brown is facing between 72 years to life in prison if he is convicted for these attacks.