The governor of a province in north-eastern Colombia has declared a state of emergency over fighting between rival rebel groups.
William Villamizar, governor of Norte de Santander, said the measure was necessary to assist people displaced by the clashes.
He said about 1,000 families had fled the fighting and 4,000 children were unable to go to school.
The EPL and the ELN are fighting for control of a coca-growing region.
Much of the Catatumbo region on the border with Venezuela used to be under the influence of the Farc rebels.
They signed a peace agreement with the government of President Juan Manuel Santos in 2016 and the group has now become a political party.
But its demobilisation left a power vacuum in many areas, as the government has been unable to impose its authority over some of the most remote regions in the country.
On Sunday, rebels from the EPL, or Popular Liberation Army, declared an "armed stoppage" in the region which closed businesses and left many roads empty of traffic.
It says the much larger ELN, or National Liberation Army, has been trying to evict it from the region and has promised to fight back.
The Colombian government suspended peace talks with the ELN in January following attacks in the north of the country which left seven police officers dead and 47 people injured.