Guatemala has given the army special powers to reclaim control of the northern province of Alta Verapaz, which officials say has been overtaken by Mexican drug traffickers.
The move allows troops to hold suspects and conduct searches without warrants.
Security forces are looking for members of the Zetas drug gang, which has been expanding its operations from Mexico.
All cars entering and leaving the provincial capital, Coban, were being inspected.
The special powers will remain in place for at least 30 days, government spokesman Ronaldo Robles says.
Mr Robles said the Zetas cartel took control of Alta Verapaz more than a year ago, spreading fear among the local population.
He said that the police force in the province had been "totally infiltrated by the Zetas", guaranteeing "total impunity" for criminals.
He told a news conference that the cities of Coban and Carcha had become a gateway for the drugs trade.
Guatemala is seen as a major transit point for cocaine smuggled from Colombia through Guatemala to Mexico and on to the US.
The Zetas gang is one of Mexico's most powerful and violent drug cartels.
Guatemalan law enforcement officials say the gang has increasingly moved its operations south since Mexican President Felipe Calderon stepped up his country's fight against the drugs trade.