WATCH: Barges hit dam in Oklahoma along river strained by floodwaters

UPDATE: The Tulsa District U.S. Army Corps of Engineers says, based on initial observations, the structural damage to an Oklahoma dam hit by two barges Thursday is minimal.

On Facebook, the district said engineers “found no integrity issues that make us concerned that it (the dam) will not perform as designed,” but they will continue to monitor and assess the dam as water conditions change.

The barges, owned by Oakley Transport, hit the dam around 11:58 a.m. They were carrying 1,500 tons of phosphate-based fertilizer, which the district said is nontoxic. The current water conditions make it unclear how much barge debris may have passed through the dam, the Corps said.

WEBBERS FALLS, OK (KFOR/NBC) — A pair of barges slammed into a dam after they broke free from their moorings on the swollen Arkansas River Thursday in Oklahoma.

Aerial footage shows the moment both barges slammed into the Webbers Falls lock and dam, east of Oklahoma City.

One barge immediately sank, while the other went down within a minute.

Officials said the barges first became stuck on rocks, but the fast moving water eventually broke them free.

The dam did not appear to be damaged, but emergency management officials ordered mandatory evacuations for everyone in Webbers Falls while engineers continue to assess it. The dam was already under strain from floodwaters when the barges hit.

Thursday evening,