Bahraini security forces launched a manhunt on Saturday after a reported 20 prisoners broke out of a jail on the island of Muharraq, site of the Gulf state's main airport.
There was no immediate word on whether the prisoners were common criminals or political activists jailed.
The interior ministry said police had recaptured some of the fugitives but gave no details on how many remained at large.
It said the breakout happened at the Al-Hadd detention centre near the Muharraq dry dock on Friday evening.
Bahrain's Akhbar Al-Khaleej newspaper said around 20 prisoners had escaped.
"They managed to seize a bus and get away after assaulting warders and police and wounding several of them," the paper said.
Police set up roadblocks on the causeways linking Muharraq to Bahrain's main island, where the capital Manama is located, the paper added.