Texas reliever Frank Francisco was arrested yesterday morning on a charge of aggravated battery after he threw a chair into the right-field box seats and hit two spectators in the head during Monday night’s loss to the Oakland Athletics.

One of the fans, an unidentified woman, was bloodied and her nose was broken.

Major League Baseball’s commissioner’s office said yesterday morning that it was investigating. Francisco was taken from the stadium to jail, where he was booked, fingerprinted and his mug shot was taken. He was released about two hours later on $15,000 bail, Oakland Police spokeswoman Danielle Ashford said.

With two outs in the ninth inning, the Rangers’ Alfonso Soriano tied the game 5-5 with his second homer of the night. Moments later, with Hank Blalock at the plate, the Texas bench and bullpen cleared.

After the game, Rangers manager Buck Showalter said the fans “went over the line.”

“It was a real break from the normal trash you hear from fans. We’ve had problems about every time we’ve come here,” he said.

But on yesterday, Texas owner Tom Hicks apologized “for the conduct of some members of our club last night in Oakland.”

“Their behavior, especially the injury to a fan, was unacceptable. Even in a difficult or abusive environment, players should never be provoked into such actions,” Hicks said in a statement, adding that he had been in contact with the commissioner’s office. He did not say whether Francisco or any other player would be punished.

Athletics spokesman Jim Young said the fans involved “were not in the wrong in any way.”

Texas reliever Doug Brocail was seen screaming at a male fan, and the pitcher had to be restrained by his teammates and bullpen coach Mark Connor. Others also had to be held back.

Francisco threw the plastic ball-boy’s chair at a fan in a lower box near the Rangers’ bullpen along the right-field line. The chair hit one man in the head, then bounced and struck the woman on her left temple.

Security ran to the scene and a small section of fans was cleared from their seats.

A’s manager Ken Macha came across the field to speak to Dave Rinetti, vice president of stadium operations, before play resumed 19 minutes later.

There was talk between the umpires and managers of suspending the game, clearing the stands and forfeiting the game, which Oakland won 7-6 in 10 innings.

“From what I understand, there was some calls made to security early during the game but I have no idea what started it out there,” crew chief Joe Brinkman said.

After the game, Francisco was escorted by police into a car that had been driven onto the field after the stadium was cleared out.

The injured woman was treated at a hospital for facial cuts and a broken nose, the A’s said.

Ashford declined to identify the woman beyond saying she was married to a man who was heckling the Rangers players. Police have decided to refer the case for prosecution since the charge is a felony, Ashford said.

Oakland team officials could find no evidence that any of the fans were at fault, Young said.

“This incident escalated to ugly proportions last night when Ranger players made a very unwise choice to attempt to enter the seating area and one player threw a chair that caused bodily harm,” Young said.

Brocail declined to comment after the game.

Francisco, 25, was the American League rookie of the month for August, when he was 3-0 with a 1.69 ERA.

The teams meet again yesterday night in Oakland. Extra security, especially around the Rangers’ bullpen and dugout, was going to be provided, Young said.

Francisco isn’t the first baseball player to face charges for a brawl — last year, former New York Yankees Jeff Nelson and Karim Garcia and a Boston Red Sox groundskeeper were charged with assault and battery for a bullpen fight during the AL championship series.

Fans at A’s games have also been rowdy in the past. Last season, one was charged with assault after throwing a cell phone from the second deck that hit outfielder Carl Everett, then with the Rangers, in the back of the head.

During the 2000 season, 19 Los Angeles Dodgers players and coaches were suspended, and three fans were charged with disorderly conduct, after a brawl at Chicago’s Wrigley Field. The brawl started when a fan allegedly struck Dodgers catcher Chad Kreuter in the back of his head and snatched his cap as Kreuter sat in the bullpen.

In 2002, Kansas City first base coach Tom Gamboa was attacked by a father and son who ran onto the field during a game at Chicago’s Comiskey Park. Gamboa was left with damage to the hearing in his right ear. The next season, again at Comiskey, a fan ran onto the field and attacked umpire Laz Diaz.