Pedro Martinez (search) was hit in the forehead by a baseball thrown from the banks of the Charles River while he was riding on an amphibious vehicle during the World Series victory parade for the Red Sox. He was not seriously injured.

"I have a little headache, but I'm OK," Martinez said after the parade ended Saturday at Fenway Park.

It was not immediately clear who threw the ball or why.

Martinez looked stunned, putting his hand to his forehead. The ball was later seen floating in the water as the vehicle floated down the river for the final leg of the parade.

Jim Averill, 42, of Boston, said the ball was thrown at a high speed from the river bank. He said pitcher Derek Lowe (search) tried to catch it before it struck Martinez.

"I saw the ball hit him in the head," Averill said. "Derek Lowe tried to grab it. It hit him and it flew up about 15 feet and fell into the water."