Story highlights Mexico's state oil company says 26 workers died

The blast occurred near Reynosa, Mexico

A fire that occurred after the blast has been extinguished, Pemex says

At least 26 workers died in a blaze Tuesday at a Mexican gas facility near the Texas border, the state oil company Pemex said.

Investigators were working to determine what caused the accident, which occurred near Reynosa, Mexico.

Four of the dead were employees of the state oil company and 22 were contractors, Pemex said.

The fire, which occurred after a blast at the facility, had been extinguished as of Tuesday afternoon, the company said in a Twitter post.

"The fire is extinguished, and the situation is under control," Pemex said.

Some pipes and valves were damaged, Pemex said.

At the facility, gas is processed from Mexico's Burgos field.

In recent years, explosions and fires have been reported after illegal tapping of the state oil company's pipelines.