The Coast Guard closed a small section of the Upper Houston Ship Channel to deep-draft ship traffic after a tug and barge sank on the waterway Monday morning.

The affected area is approximately 1,000 yards long and located approximately two miles east of the Interstate 610 bridge across from the Kinder Morgan terminals in Galena Park, Texas.

The 25’8”x16’x4’5” harbor tug Annie Moon, owned by Cedar Bayou Towing, was attached to a 200-foot barge that was carrying 60’-80’-long sheets of metal, each 2’ wide and a half-inch thick. At approximately 5 a.m., crew aboard The Enterprise, a tug across the channel, called the Coast Guard vessel traffic service when they heard what they described as lines parting as the Annie Moon and attached barge sank where they were moored.

Upon notification of the incident, the Coast Guard restricted the area traffic to one-way. After assessing the situation by boat and helicopter, the agency learned that approximately 20 gallons of diesel fuel leaked from the tug, which was carrying about 300 gallons. The area was boomed off to contain and recover any additional spill while the vessels are being recovered.

Big John, the Big John Marine heavy lift cargo crane, was expected to begin work lifting the sunken tug and barge Monday afternoon. The Coast Guard said it would work with responders to ensure the barge and its cargo are clear of the ship channel before reopening it to all traffic. Barge traffic was being allowed through Monday afternoon, one at a time.

The cause of the incident is under investigation.

UPDATE: The affected section of the Houston Ship Channel was reopened to all traffic on Oct. 22, 2015.