BAYPORT, Texas (AP) " Officials say air monitoring hasn't raised health concerns as cleanup efforts continue following a collision at a busy commercial waterway near Houston involving four vessels that caused a toxic gasoline product to leak into the water.

Authorities said air testing Sunday found one detectable concentration of a volatile organic compound that was not detected in subsequent tests.

Residents in cities near the accident site have reported a strong gasoline smell. Officials say the spilled product is toxic to touch, inhale or ingest.

Friday's accident near Bayport, Texas, between a tanker that punctured storage tanks on a tugboat that was pushing two barges along the Houston Ship Channel released about 9,000 barrels of a gasoline blend stock.

The ship channel remains partially closed.

The cause of the collision is being investigated.