The families of two men presumed dead after scaffolding collapsed under a bridge 100 feet over the Arkansas River filed a lawsuit Monday against two construction companies and a foreman in charge of the bridge project.

Juan Manuel Flores' wife and Manuel Gonzalez's brother filed their suit in state district court in Dallas County. They're seeking unspecified damages and medical, funeral and burial expenses.

The April 2 accident killed a third man whose body was found eight hours later in the rainswollen river. A body was found Sunday in the Arkansas River near the accident site but wasn't immediately identified, officials said.

The workers were installing a water main for the Central Arkansas Water utility.

The lawsuit said Oscar Renda Contracting of Roanoke and SAC Manufacturing of Longview "knew that hazardous and dangerous conditions existed" but failed to warn workers. The lawsuit accuses both companies and project supervisor Charles Jackson of gross negligence.

The lawsuit accuses SAC Manufacturing of inadequate design and testing of the work platform that plunged into the river. The company failed to determine the load capacity for the platform, according to the lawsuit.

Jackson and the two companies did not immediately respond to messages left Monday by The Associated Press. On the Oscar Renda Contracting Web site, the company advertises a memorial fund for the families of the three workers.

"The fact that these three men were allowed to work on this scaffold platform ... is a blatant disregard for safety," said Clay Miller, a lawyer for the plaintiffs.

The lawsuit also claims both companies violated federal safety standards. The federal Occupational Safety and Health Administration said Monday it is investigating the incident.

Associated Press reporter Jeff Carlton in Dallas contributed to this story.