LOS ANGELES >> A tip from a parole officer led to the arrest of one of the suspects in the attack on a San Francisco Giants fan outside Dodger Stadium after the rival teams’ season opener, a brutal beating that prompted an outpouring of support for the victim and outrage in the sports world and beyond.

The man detained early Sunday is believed to be the "main aggressor" in the March 31 beating that left Bryan Stow with brain damage, Los Angeles Chief Charlie Beck said at an afternoon news conference at the stadium.

An emotional Beck hailed the work of 20 full-time detectives who he said have pursued 630 leads in the case so far.

The suspect, whose name was not immediately released, was among several people detained for questioning after police served search warrants, Los Angeles police Det. Jose Carillo said. Police said he was one of two suspects that have been sought in the case.

He was expected to be booked Sunday night.

It’s unclear whether the others detained were possible witnesses or suspects in the March 31 beating that left Bryan Stow with brain damage, said police Sgt. Kunch, who declined to give his first name per department policy.

Several search warrants were served at an apartment building, Kunch said, but he couldn’t say how many people were detained or whether they are male or female. Building manager Maritza Camacho told the Los Angeles Times that a SWAT team descended on the East Hollywood apartment using loudspeakers and with guns drawn.

Among the people taken out of the building was a man with a bald head and tattoos on his neck and arms, Camacho said, a description that appeared to match the vague sketches released by police of one of the two suspects.

Stow, a 42-year-old paramedic and father of two, was beaten in a parking lot by two men in Dodgers gear after the season opener against the Giants. No arrests have been made.

Last week, doctors reported that Stow is able to open his eyes but remains in critical condition after being transferred to San Francisco General Hospital. Stow had been at Los Angeles County-University of Southern California Medical Center since the attack that forced doctors to put him into a medically induced coma to avoid having seizures.

Police Chief Charlie Beck said recently that detectives are looking into about 500 leads in their search for the attackers. Rewards totaling more than $200,000 have been offered for information leading to the suspects’ arrests.

Stow’s sister said police called her family Sunday morning to inform them about the search warrants.

"I can’t even tell you the emotions that we’re going through right now," Bonnie Stow told KABC-TV, occasionally choking back tears. "To be excited is the least we can say."

An outpouring of support for Stow included fundraisers that ranged from bowling tournaments to pasta dinners to donated services such as haircuts and fitness classes. The events are listed on the family’s blog.

San Francisco Mayor Ed Lee said after hearing the news Sunday he called Los Angeles Mayor Antonio Villaraigosa to express his thanks for the efforts of LA authorities and to congratulate him.

"That sort of brutality is totally unacceptable," Lee said of the attack. "It’s not only unacceptable, but needs to be dealt with. Our hearts are still open for a full recovery of Mr. Stow."

Giants manager Bruce Bochy said he heard Sunday morning that a suspect was in custody.

"Great news. It’s been hard on the family," Bochy said before the Giants hosted Oakland. "For them to work as hard as they have been, I’m talking about the police department, to have a suspect in hand is great news. Hopefully they’ll catch everybody who was involved in this senseless act."

Giants team officials also released a statement commending Los Angeles police and thanking "the community for its tremendous support for the Stow family during this difficult time."

Giants fan Les Wong, 37 of San Francisco celebrated the news as he headed to the game.

"It’s good to hear that they caught someone. That kind of thing doesn’t belong in sports," said Wong, who was wearing a Giants hat and Giants t-shirt. "I’m glad to hear there is going to be some sort of justice."

Stow, who was wearing Giants gear, was leaving the game at Dodger Stadium with two friends when he was attacked. Moments earlier, Stow texted a family member to say he feared for his safety in the rowdy crowd.

Following the attack, Beck beefed up security at Dodger Stadium to deal with fights that had been breaking out at games in recent years.

Baseball fans have complained that anyone who dares to wear a rival team’s jersey on Dodger turf has too-often been subjected to profane verbal abuse and threats of violence.

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Associated Press reporters Thomas Watkins and Andrew Dalton in Los Angeles and John Marshall and Antonio Gonzalez in San Francisco contributed to this report.