India has alerted Interpol after 18 priceless antique Buddha statues were stolen from a Bihar museum, police say.
Police say robbers broke in through a first-floor window and stole the 9th and 10th century works at the weekend.
The museum director called the theft of the bronze statues, insured for millions of dollars, "a major loss".
The museum in the Bihar state capital, Patna, is next to a police station and correspondents say the incident is a major embarrassment for police.
The antiques date from the Pala dynasty, which ruled the Bihar and Bengal regions of South Asia from the 8th to the 12th centuries.
The Pala empire is noted for its art and architecture, and in particular for its distinctive Buddhist sculptures.
Bihar Chief Minister Nitish Kumar convened an emergency meeting of police and security officials on Tuesday night.
Major domestic and international airports have been put on alert across India.
Forensic experts are examining fingerprints at the gallery and police say they suspect the involvement of a major international criminal gang.
Bihar has a reputation has India's poorest and most lawless state.