A truck passes as smoke billows from the BP oil refinery plant after an explosion. (AP photo)

An explosion at a Texas oil refinery has killed at least 14 people and injured more than 100.

It isn't known what caused the blast, which ripped through the British Petroleum refinery in the middle of the afternoon.

The explosion was felt more than eight kilometres away and caused significant damage to nearby offices, and cars and trucks in the parking lot.

BP's Texas City plant stretches across 480 hectares and is made up of 30 refinery units. The plant processes about 435,000 barrels of crude oil per day and employs about 2,000 people.

The company claims its plant produces three per cent of all the gasoline consumed in the United States.

News of the accident pushed gasoline futures higher in after-hours trading.