HOUSTON (AP) — The U.S. Coast Guard says it's unclear when the Houston Ship Channel will fully reopen as crews continue cleaning up chemicals that seeped into one of America's busiest shipping lanes following a fire at a petrochemical storage facility.

Coast Guard Capt. Rich Howes said Monday that cleanup crews are making headway and that more than 2.5 million gallons of an oily water mixture has been removed.

Part of the ship channel was closed after a fire erupted March 17 at the Intercontinental Terminals Company facility in Deer Park. The fire burned for days and triggered air quality warnings. The closed portion was reopened but only during daylight hours.

The U.S. Environmental Protection Agency says elevated benzene levels were detected over the weekend, but that residents are not in danger.