Officials are investigating the cause of the failure, he said.
Officials are also investigating reports of drug use at the construction site.
Officials are investigating whether they were caused by a common environmental factor.
Officials are investigating whether alcohol played a role in the fight.
It declined to say what the federal officials were investigating.
But when the girl never showed up there, officials did not follow procedures and investigate what had become of her.
He said officials were investigating reports that two more may have also been injured.
Officials are also investigating reports that an entire village was swept away.
Officials are still investigating the four bombing incidents in the South.
American officials are investigating whether there was any insider trading.