CHICAGO — For the New York Mets, it was a grand slam of an inning.

First, Cliff Floyd homered with the bases loaded. Then, Carlos Beltran did the same. After David Wright added a two-run shot, New York had 11 runs — the most in a single inning in club history.

"It was just amazing to keep going like that. You never think you're going to score 11 runs in one inning," Floyd said last night after Mets' sixth-inning outburst sent them to a 13-7 victory over the Chicago Cubs.

It was one of those hot summer nights at Wrigley Field where the wind is blowing out and the ball is flying over the wall.

New York sent 16 batters to the plate in the sixth and benefited from two errors on Cubs second baseman Todd Walker that led to eight of the 11 runs being unearned. The half-inning, on a muggy 95-degree night, took 41 minutes to play and saw the Cubs make 70 pitches.

"You walk up to the plate and you have to start asking questions of the umpire and to the catcher. I know Michael Barrett. 'Have you ever see anything like this?' " Floyd said. "He said, 'No, I haven't.' It's kind of nothing you can do, wind blowing out, you make pitches and we put swings on them and it happens."

The Mets' outburst marked the first time a team had two grand slams in an inning since April 23, 1999, when St. Louis' Fernando Tatis hit two in the third at Los Angeles.

"Obviously in this ballpark, anything can happen at any time," Mets manager Willie Randolph said.

"It was a total nightmare. We gave them too many outs. A team like that who can score runs, you can't give them outs," Cubs manager Dusty Baker said. "I've never seen two grand slams in the same inning."

New York trailed 5-0 after two innings before showing why it is the highest scoring team in the National League and the one with the best record (55-37).

Floyd's grand slam was a liner to left field off Sean Marshall (5-8). Beltran hit his grand slam into the seats in left-center off off reliever Roberto Novoa, who also allowed Wright's two-run shot.