CHICAGO (AP) – Major league baseball will review security at ballparks nationwide to try to prevent fan violence following the attack on an umpire at a White Sox game.

Top baseball officials were in Chicago on Wednesday to investigate the assault on first base umpire Laz Diaz, which raised concern and questions throughout the majors.

It came just three months before U.S. Cellular Field hosts the All-Star game and about seven months after a similar attack on a first base coach at the stadium.

Baseball commissioner Bud Selig said he was extremely troubled by the assault Tuesday night during the game between the White Sox and Kansas City Royals.

“There is no place in baseball for such deplorable fan behavior and we urge that the guilty parties be prosecuted to the fullest extent of the law,” Selig said.

Kevin Hallinan, major league baseball’s security chief, and Sandy Alderson, executive vice president of baseball operations in the commissioner’s office, were looking into the attack. Selig said baseball would re-examine security at all stadiums.

Last September, Kansas City coach Tom Gamboa was pummeled by a father and son just yards from where the fan ran onto the field and tried to tackle Diaz by grabbing him around the waist.

Security and players rushed to help the 40-year-old Diaz, who served in the U.S. Marine Corps Reserve.

“I just turned around and got him off me,” he said. “The good hand-to-hand combat they taught me worked.”

Diaz was not hurt, but the fan, who’s name was not released, needed treatment for minor injuries at a hospital after being thrown to the ground and roughed up by players. He was later seen with a bloody bandage on his head.

Police did not immediately file charges against the fan, who was led away in handcuffs and remained in custody. His motive was not disclosed and it was unclear whether he had been drinking alcohol.

White Sox spokesman Scott Reifert said security was being beefed up for Wednesday night’s game. Kansas City general manager Allard Baird told The Kansas City Star that his team planned to stay off the field unless its safety was assured.

Three other fans also charged onto the field Tuesday night – getting close to players – and were charged with misdemeanor criminal trespassing. They sprinted across the field until security guards tackled them.

Across town at Wrigley Field, Cubs general manager Jim Hendry said he’s satisfied with the security and no changes were made for Wednesday’s game against the Cincinnati Reds.

Still, he said there’s only so much that can be done to keep fans from running onto the field during games.

“You still couldn’t prevent a person, one lunatic or whatever you want to call it, from trying to get his 10 seconds of fame,” Hendry said. “I don’t think you could ever say you’re going to prevent it completely in any stadium: football, basketball, baseball, whatever.”

Wrigley was the site of a fan-player fight three years ago when members of the Los Angeles Dodgers went into the stands after a fan stole a player’s cap.

At Yankee Stadium in the Bronx, team spokesman Rick Cerrone said security might be reviewed but called the ballpark very safe.

Umpire Mark Hirschbeck said everyone on the field is vulnerable, but solutions are limited.

“You know, anybody can jump on the field and get to somebody, whether it be a player, coach or an umpire, and there’s a lot of kooks out there,” Hirschbeck said. “You don’t know what they’re going to do.”

“I think all you can do is defend yourself, do the best you can. Unless they put up big glass things on the side, and I don’t think they’re going to do that.”

The 55-year-old Gamboa still has slight hearing loss in his right ear from last year’s attack.

Now the Royals’ bullpen coach, he said he thought security was tighter for his team’s return. He felt safe – at least before the game.

AP-ES-04-16-03 1702EDT