CORPUS CHRISTI, Texas (AP) — Six people have been hospitalized after a natural gas pipeline exploded Friday in the Port of Corpus Christi, authorities said.

“The Fire Department is still conducting search and rescue operations with the Coast Guard at the Port of Corpus Christi, looking to see if there’s anybody else that was impacted, but we haven’t found anybody else so far,” Corpus Christi Fire Department Chief Robert Rocha said late Friday morning.

He said that upon arrival, firefighters had “encountered heavy fire and smoke conditions.” By late Friday morning, the supply line feeding fire had been shut off and it was going out, Rocha said.

A barge and a pipeline were involved, Rocha said, but they were still investigating what caused the explosion and fire. Another official earlier said a barge in the water hit the pipeline.

The Port of Corpus Christi said in a statement that a natural gas pipeline was involved and that operators had isolated it.

Rocha said that of the six people transported to a hospital, one was in serious condition. He said the Fire Department transported four people to the hospital, while the U.S. Coast Guard transported two.

Texas Gov. Greg Abbott issued a statement saying that the state was working closely with authorities in the area and that the Texas Commission on Environmental Quality was monitoring the air quality.

Rocha said most of the heavy smoke was blowing into a rural area.