The press service for the Kyrgyz Border Guard service said all traffic across the border was halted after a police post in Khanabad was attacked overnight. The press service said some deaths were reported.
Residents of the nearby town of Andijan told Reuters news agency that armoured vehicles could be seen on the streets.
Khanabad is in Andijan province, where Uzbek government forces opened fire on demonstrators in 2005. At least 187 people were killed, according to authorities, in the unrest.
Human rights groups said several hundreds of civilians were killed in the crackdown which provoked international condemnation of the Uzbek government.
The authorities said troops had been provoked by Muslims opposed to the government.