A man is holding dozens of people hostage on a bus in Brazil, and is threatening to set the vehicle on fire, according to local police.
Negotiations are underway with the man, who is armed, the Federal Highway Police said in Rio de Janeiro.
At least six hostages have been released so far, but the man has poured petrol on the bus, and is threatening to set it alight.
The incident began on the busy bridge linking central Rio with the suburb of Sao Goncalo at about 5.30am local time.
Officers said the man has identified himself as a policeman, although this has not been confirmed.
Authorities said the man had not made any particular demands and appeared to have “psychological problems”.
Rio’s elite police force known as BOPE is in charge of the negotiations. A sniper has been placed nearby.
Traffic has been blocked in both directions on the bridge, with hundreds of vehicles waiting in line.
Sao Goncalo is a violent, impoverished suburb separated from Rio by Guanabara Bay.
Some 37 people were thought to be trapped.
Additional reporting by agencies