Arauca has long been a stronghold of the country's two main left-wing guerrilla groups, the Revolutionary Armed Forces of Colombia (FARC) and the National Liberation Army (ELN). After a long period of peaceful coexistence, the two started fighting each other last year. The reasons are still not clear.
Caught in the violence, local people are fleeing from rural areas to take refuge in cities and small towns like Arauquita. Local officials say there is a marked increase in cases of forced displacement.
"We are overwhelmed," admitted a local official responsible for receiving the statements of families arriving in Arauquita. "The numbers are astronomical, we just don't know what to do with them," she said, adding that the true scale of the displacement was not known because many people were too scared to register.
Some 1,000 people have come forward in the past 18 months and said violence had forced them out of their homes in a town that had previously counted only a few displaced families. The increase reflects a departmental trend: displacement figures in Arauca went up by 88 percent between 2005 and 2006. Initial numbers for the first six months of this year show no let-up.
UNHCR works in Arauca through a network of partners, including the Catholic Church and La Defensoria del Pueblo, Colombia's human rights network. In view of the serious humanitarian situation, the refugee agency is stepping up its presence on the ground and took part in a fact-finding mission earlier this month to help tailor its intervention to meet the needs on the ground.
Bordering Venezuela, Arauca is a largely rural, cattle-rearing region, but it also has rich oil reserves. Most people live on farms, often far from the villages. Until last year, Arauquita had around 6,000 inhabitants - the unexpected influx of displaced people has boosted its population by almost 20 percent.
"There are three or four families to a house. We had to build where we could, too close to the river. Now with the rainy season we're all worried about flooding," said a 35-year-old who arrived last August. He is a member of the local association for displaced people and, like everyone else in Arauquita, he does not want to be named.
The town is far from being a safe haven. A few days before the UNHCR team visited, unidentified gunmen shot dead local right-wing councillor, Alejandrina Rincon, in broad daylight as she walked in the town with her eight-year-old son. She had been threatened and other local leaders have also received threats.
In the past two years, 10 teachers have also been targeted by one or other group and five had to flee. With local elections coming up in October, many are scared that more violence is on its way.
In the scores of small villages dotted along the vast plains of Arauca, the situation is worse. This is where the fighting between the rival guerrilla groups is at its most intense. People say the army and police are there only intermittently, if at all.
"People there live very badly. They go to bed at night wondering who's going to wake them up and tell them they have to go," said one farmer, who had fled to Arauqita a couple of weeks earlier. "Or to kill them," another man adds.
When asked how many people have arrived in recent weeks, the men start counting. Three from this parish, five from that village, another two just this weekend: the list goes on and on. Others have crossed the Arauca River to take refuge in Venezuela.
One of the older farmers shook his head. He didn't have time to take anything with him when he fled his farm at three in the morning. "It was my father's farm before it became mine; we brought up five children there. It's hard, but we are the lucky ones. The dead can't be displaced."
Marie-Helene Verney in Arauquita, Colombia