Another explosion-fire at Exxon Baytown, TX, Chemical plant.

HOUSTON (Reuters) - A naphtha processing unit exploded at the Exxon Mobil Corp. Baytown, Texas, chemical plant early on Thursday morning but there was no indication of foul play, a company spokeswoman said.

The explosion in a "naphtha rerun unit" occurred at 1:30 a.m. CST, said Exxon Mobil spokeswoman Tricia Thompson.

A fire following the explosion was out by 2:30 a.m. CST (0830 GMT), Thompson said.

"There is no indication of foul play," Thompson said.

Other units at the chemical plant continue to operate normally as does the adjoining 525,000 barrel per day (bpd) Exxon Mobil Baytown, Texas, refinery, the largest U.S. refinery.

This is the second explosion at a refinery/chemical plant complex in Texas this week.

On Tuesday night, an ultraformer at BP Plc's 460,000 bpd refinery in Texas City, Texas, blew up and burned. The cause of that blast is believed to be accidental.