LOS ANGELES -- A tip from a parole officer led to the arrest Sunday evening of one of the suspects involved in the brutal attack on San Francisco Giants fan Bryan Stow outside of Dodger Stadium on Opening Day.

Police booked 31-year old Giovanni Ramirez of Los Angeles for assault with a deadly weapon and are holding him on $1 million bail. He was apprehended early Sunday morning during a dramatic raid by S.W.A.T officers at an apartment in the Rampart area of Los Angeles, approximately five miles from Dodger Stadium.

Ramirez is believed to be the "primary aggressor" in the Stow beating, Los Angeles Chief Charlie Beck said at an afternoon news conference at the stadium. However police are still looking for the other suspect in the attack, and a woman wearing an Andre Ethier jersey who helped the suspects flee in a white Mitsubishi or Acura after the attack.

Los Angeles police arrested Giovanni Ramirez, 31, at this apartment complex in Los Angeles on Sunday. Ramirez is the main suspect in Bryan Stow's beating, according to police. Ramona Shelburne

Stow suffered brain damage in the attack and remains in critical condition at San Francisco General Hospital.

The reward for information leading to the arrest and conviction of Stow's attackers grew to over $250,000 after the Dodgers committed an additional $100,000 earlier this week. The reward is still being offered, as police continue their investigation.

The apartment building, located in the 800 block of North Mariposa Avenue, sits squarely in the territory of one of Los Angeles' most dangerous street gangs.

Beck acknowledged Sunday that the area where Ramirez was apprehended is the territory of several street gangs, but would not say whether Ramirez was part of one of those gangs.

Several neighbors interviewed by ESPNLosAngeles.com said they believed he was and that they feared retribution for speaking to reporters or the police about Ramirez.

"We still have to live around here," said a man in his late 40s, who was sitting outside a house next door to the apartment building where Ramirez was apprehended Sunday morning. The man said he did not wish to be identified because he feared retribution, but he said that he knew Ramirez and had spoken to him recently.

"You only get the reward after he is convicted and we still have to live here until then."

Beck, Los Angeles Mayor Antonio Villaraigosa, Councilman Ed Reyes and Dodgers vice president Howard Sunkin were all present at the news conference.

Beck said the department had received more than 630 leads from the public and other sources in the seven-week investigation. Twenty of the departments top detectives worked more than 6,000 combined hours on the case, chasing tips from San Francisco to San Diego.

Police said tips in the case dramatically increased after 300 billboards with composite sketches of the suspects were put up around the city over the last two weeks, a gesture funded by Lamar Advertising Co.

Beck seemed emotional as he hailed the work of those detectives and recalled the phone call he received from assistant chief Earl Paysinger early Sunday morning, informing him the operation had been successful.

"He said the words I've been waiting for for seven weeks. He said that we had Bryan's assault suspect in custody," Beck said. "This is a huge step."