At least 80 people are dead and more than 11,000 have been forced to flee their homes in Colombia, officials say, amid fierce clashes between two rival armed groups on the border with Venezuela.

The violence, in a northeast region called Catatumbo, is some of the worst the country has suffered through in recent years, raising concerns that the country is moving in the opposite direction of “total peace” — a goal made a priority by the country’s leftist president, Gustavo Petro, who is more than halfway through his four-year term.

The Colombian leader visited the region on Friday, writing that on X that his government “stands with the people of Catatumbo.” He has also sent troops and humanitarian assistance.

Displaced families are taking refuge in a stadium in Cúcuta, a border town better known in recent years for receiving Venezuelan migrants. In some places, Colombians are fleeing into Venezuela — home to its own humanitarian crisis — and the Venezuelan autocratic leader there, Nicolás Maduro, has promised to send them aid.

The clashes in Catatumbo are a stark departure from the hope that swept across parts of Colombia less than a decade ago, when the country signed a peace deal with its largest rebel group, the Revolutionary Armed Forces of Colombia, or FARC.

The nation had suffered through decades of internal conflict, with left-wing guerrilla groups, including the FARC; paramilitary organizations; and the government fighting for control of the country and for lucrative industries like narcotrafficking.