All but one of 23 oil workers kidnapped on Monday in eastern Colombia have regained their freedom, officials said on Tuesday.

“We can confirm that 22 of the 23 are now freed,” Defense Minister Rodrigo Rivera said shortly after government sources said that 19 workers had been released.

One of the workers successfully escaped and 21 were freed, Rivera said, attributing the result to pressure asserted by security forces that were still combing the area in an effort to rescue the remaining abductee.

Colombian President Juan Manuel Santos welcomed the news and congratulated the army for its success in liberating the kidnapped workers, saying it was a reason for celebration.

“This is a very important message. When we are informed in a timely manner about such unfortunate events, then the public forces will react and the probabilities for securing the release successfully are very high,” Santos told reporters in the capital, speaking on the sidelines of an event celebrating International Women’s Day.

The 23 workers, all Colombians employed by the Canadian Talisman Energy company, were kidnapped on Monday in the eastern state of Vichada, a stronghold for the rebel Revolutionary Armed Forces of Colombia.

The escapee slipped away on Monday night and gave military troops the information needed to pursue the kidnappers, the defense minister said.

Rivera said that military operations will continue until the last man in captivity is also freed.

Possibility also remains that the man has managed “to run away and is waiting for the army troops to locate” him, the minister added.

Violence and kidnappings have markedly decreased in recent years in Colombia, as investment in its oil and mining sectors is on the rise. However, illegal armed groups still pose a threat in remote areas.