US correspondent Duncan Kennedy: "Every piece of wood is unstable "

Dozens of students were climbing on the stack at A&M University, Texas, when it suddenly collapsed at 0230 CST (0830GMT).

The Thanksgiving Day bonfire has been a tradition since 1909 to get fans in the mood for the American football game between A&M - known as Aggies - and arch-rival, University of Texas.

Around 28 students were injured. For hours, rescuers pulled people free from between the logs. One person was not freed until more than six hours after the collapse.

Students consoled each other

When workers said they heard a "moaning and tapping sound," spectators were asked to be quiet so they could hear if anyone was still alive.

Cranes removed logs gingerly - one by one - to search for others possibly trapped.

Jenny Callaway, a student who was on the stack, said it just fell. She said there was no warning. "It just snapped," she said.

Bart Humphreys, a fire department spokesman, said: "Every piece of wood in that pile is unstable and every piece of wood that moves affects other pieces of lumber."

Survivors were taken to the nearest hospital

University president Ray Bowen said: "It's an extremely sad occasion (for) the Aggie community."

Texas Governor George W Bush said his thoughts were with the parents of the students killed.

"I just can't imagine what that means to have that happen to them," the governor said in a television interview. "It's sad, it's tough."

The logs had been piled up for the traditional bonfire at the university, about 130km (80 miles) north-west of Houston.

The pile would have reached 18 metres

Lit the evening before the match, tradition has it that if the logs topple before midnight, then A&M will lose the game. But if the logs burn into the morning, A&M will be victorious.

Thousands of logs are stacked high to build the bonfire, using cranes, tractors and crews of students. Students involved in the project get safety training in advance.

In 1994, a stack collapsed and a second was built and set on fire.