One guard was killed and another suffered multiple gunshot wounds in the daring midday raid, which ended with rebel chief Gustavo Anibal Giraldo fleeing on the back of a motorcycle, authorities said. A drug-sniffing police dog also was killed.
Giraldo was about to be taken to a court hearing outside the prison when three guerrillas on two motorcycles zoomed in for the attack about 11:40 a.m., the INPEC national prison service said in a statement.
The jailbreak in the northeastern city of Arauca came less than six weeks after Colombia's Supreme Court denied a U.S. request to extradite Giraldo, who also is known by the alias "Pablo."
Giraldo allegedly ordered the 12-day detention in 2003 of photographer Scott A. Dalton and reporter Alison Ruth Morris in Arauca state. The two were released unharmed.
A leading regional commander for the National Liberation Army, or ELN, Giraldo was also charged in a U.S. indictment unsealed in December with the 15-month kidnapping of a U.S. helicopter mechanic who was working on contract in an oil extraction region.
The victim, Matthew Burchell, was freed in August 2000 after a ransom was paid, the Colombian Supreme Court said in a decision issued Aug. 26 but not publicized until late September. It said Giraldo should be tried in Colombia and not the United States because the alleged abductions occurred here.
The decision echoed a similar ruling from February, when the high court refused on the same grounds to extradite to the U.S. a rebel commander indicted in the kidnapping of three U.S. military contractors held by Colombian guerrillas for five years before their July 2008 rescue.
Giraldo was captured in January 2008 and charged with crimes including terrorism, rebellion and drug trafficking. The prison service said he was transferred to Arauca on Monday from Combita, a prison in central Colombia, a region less affected by the conflict.
The ELN, mostly dormant in recent years, is Colombia's No. 2 rebel band and has stepped up attacks the past few on police in Arauca, the movement's longtime stronghold. It has been blamed for the killings of five officers so far this year.