MEXICO CITY (AP) — The death toll in a gasoline tanker truck explosion in southeastern Mexico rose to 14 on Tuesday, the result of an attempted theft of fuel in an area that authorities say has a long reputation for roadside thefts.

Tabasco state prosecutor Fernando Valenzuela Pernas said that while investigators had found no evidence someone intentionally ignited the gasoline after the truck crashed last Thursday, people did break through the police perimeter and then chased off firefighters so they could steal gasoline.

"The stretch from Lagartero to Palo Mulato historically has been an area of robbery and assault on commercial vehicles and passengers, including a time in which they put oil on the highway to get vehicles to run off the road," Valenzuela said Monday. "It's not something recent."

He said federal police, soldiers and state police have increased patrols in the area since last year.

The Civil Defense agency had said the 15,800-gallon (60, 000-liter) tanker crashed on the road between Villahermosa and Coatzacoalcos. People ignored authorities' warnings to stay away and instead tried to take gasoline from the damaged tanker. Many suffered serious burns when it exploded.

Valenzuela said firefighters had secured 10,000 liters before they were run off by locals.

In addition to those killed, more than 20 people were injured. Authorities have not been able to interview the injured.

One of the lines of investigation is whether the fire was intentionally ignited. Rumors circulated that someone saw a young person toss a match, but Valenzuela said investigators had found no one to corroborate that.

Gasoline theft has been a persistent problem in Mexico, but siphoning directly from pipelines has received the most attention. Last month, the state-owned oil company Pemex announced that it would no longer transport finished, usable gasoline through its pipelines.