A passenger riding Muni's J-Church Metro line was stabbed by a stranger Monday, an unprovoked incident that bore similarities to an attack in September on an 11-year-old boy riding a bus, San Francisco police said.

Rachel "Ty" Brown, a 24-year-old student at San Francisco City College who moved to the city just three months ago from Portland, Ore., was riding an outbound train at Church and Market streets when she was stabbed at 10:40 a.m., said police and Brown's partner, Gabby Winder.

Brown was taken to San Francisco General Hospital, where she was in stable condition with a non-life-threatening wound to the left side of her abdomen, authorities said.

Brown was asleep next to Winder when the assailant, who had boarded at the Powell Street Station, stabbed her as he walked past the women, police and Winder said. He then fled the train.

"He didn't say anything," Winder said Monday night. "It felt like he just punched her several times. I tried to rub her side because it was hurting. Then I saw all the blood in my hand."

The operator said he did not see the stabbing, investigators said. Another passenger alerted the operator, who summoned police.

Judson True, spokesman for Muni, said the transit agency had provided police with surveillance video taken by the Metro train's surveillance cameras.

Police spokesman Sgt. Wilfred Williams said the suspect was a 6-foot, bearded African American man in his 30s with a black sweater, a black jacket and a black do-rag. "He had strong body odor," Williams said.

Police said the man was carrying tennis shoes hanging from his neck, and Winder described his pants as baggy.

The description was nearly identical to that of the man who stabbed 11-year-old Hatim Mansori at 19th and Mission streets Sept. 1 as the boy was riding the 49-Mission bus home from baseball practice. The Marina Middle School sixth-grader suffered a wound to his liver and stomach.

In that incident, the stabber was described as a "scruffy-looking" African American, in his mid-20s to 30s, 6 feet 2 and 190 pounds, with dark facial hair. He was wearing a black hoodie, blue jeans and dark shoes, and was described as having a strong body odor.

"We are aware of the similarities, and as part of the ongoing investigation will be looking at those similarities," said police spokeswoman Lt. Lyn Tomioka.

The boy's mother, Laila Elfazouzi, said Hatim has largely recovered and is back at school.

"I hope they catch him," she said of her son's attacker. "I want it over."

Winder said she assumed the man who stabbed Brown on Monday was mentally ill.

"I felt sorry for him," Winder said. "If you find him, help him. I feel bad. I didn't want the dude to go to jail, but he's not mentally there."

True said a sketch of the man who attacked Hatim has been distributed to Muni drivers, along with the description of the stabber in the latest incident.

"We want to do everything we can to assist the police in catching whoever committed these crimes," True said.