The boy was struck when Florida's Greg Dobbs hit a ninth-inning liner into the right-field seats, just beyond the New York dugout. Stadium medical workers immediately tended to the boy, who was bleeding heavily. Accompanied by his mother, he was carted away in a wheelchair after the game and taken under the stands to an ambulance.
Following the final out of New York's 2-1 victory, Mets second baseman Justin Turner went over to wait for the boy by the railing. Turner took off his jersey and handed it over as a souvenir. New York manager Terry Collins also came over, and Dobbs gave the boy a bat.
Nathan Wise, 18, and his brother Daniel, 14, from New Rochelle were sitting near the boy, who was in the front row of section 119 for the first game of a single-admission doubleheader.
"His mom stood up and was screaming for a medic. A guy came running over and took off his shirt and put it on the kid's head," Daniel Wise said.
It was unclear how old the boy was. Mets spokesman Jay Horwitz said the team could not provide any information because of medical privacy laws.
"We saw him hit a line drive and, at first, we thought we might catch it. But it went past us and we saw it hit the kid," Nathan Wise said. "We saw him put his hands out and try to block it, but he's a little kid, so his reactions were slow. We saw his hands up and then saw blood trickling down his face. A security guard called over to the Mets' dugout for some towels. It looked really serious, but after a couple of minutes, we saw the medics standing around and we realized it was bad, but it wasn't life-threatening."
Between games, the seat bottom was removed with drills, and a crew of at least four other maintenance workers were washing the area to clean up the blood.
It was the latest injury to a fan at a major league ballpark this season.
A San Francisco Giants fan was severely beaten outside Dodger Stadium in March, causing serious injuries. A man died when he fell from a stairway during a May 24 Colorado Rockies game. And a Texas firefighter tumbled over an outfield railing to his death July 7 while catching a ball tossed to him at a Rangers game.