Five sections of crowded wooden bleachers atop the grandstand at the bullring in Sincelejo collapsed yesterday and hospital officials said at least 147 persons were killed and about 500 injured.

Witnesses reported that some of the victims were impaled on splintered beams and others were trampled to death by panic-stricken crowds.

They estimated that about 3,000 persons were standing in the bleachers that crumpled along one outside wall of the bullring and fell to the ground. An estimated 40,000 fans had packed the bullring, the largest in Colombia.

Municipal authorities in Sincelejo, a cattle-raising and agricultural area about 320 miles north of Bogota, said they feared the death toll could rise as police, firefighters and civil defense teams searched through the debris.

Authorities blamed recent heavy rains for the tragedy, saying the ground under the wooden beams supporting the bleachers had become soft and the sections collapsed under the weight of the crowd.

Witnesses said the bleacher sections fell like dominoes as excited fans watched scores of youths and men in the ring evade bulls during a popular bull-running even before the regular bullfights.

The wooden bleachers were built above and extended beyond the rim of the regular grandstand. They were supported by long beams down to the ground.

"We were at the eastern-end grandstand when suddenly I noticed that one of the sections began to fall backward and then the other four fell, trapping thousands of person," said Eduardo Ruiz, one of the fans at the bullring.