A gun battle has broken out inside the headquarters of the Bangladesh border guards in the capital, Dhaka, police and TV reports say.
One person has been killed and at least six people have been wounded in a mutiny at border guards headquarters in Dhaka, Bangladesh, reports say.
There are no reports of any casualties yet in the gunfight at the Bangladesh Rifle headquarters, officials say.
Heavy fighting started at 0330 GMT and is still going on. An army helicopter patrolling above the barracks was fired at, and mortar rounds were also fired.
The BBC's Mark Dummett, in Dhaka, says that reports suggest the clashes are between officers and soldiers of the paramilitary force.
One soldier was heard addressing the mutineers by megaphone, saying they should fight the army "by any means".
The army has been called in to deal with the situation, officers say.
It comes a day after PM Sheikh Hasina visited the HQ to hand out medals.
Our correspondent says that some local TV channels are speculating that it is a mutiny by soldiers over a pay dispute.
Local media have speculated that the revolt is over pay and working conditions.
Colonel Rezaur Rahman, deputy chief of Bangladesh's internal security force, the Rapid Action Battalion, told the AFP news agency: "The army has been called in. They have already started moving to the area."
There is a heavy army and police presence at the scene. The streets have been cleared and shops have been closed.
The Bangladesh Rifles headquarters - the force protects the country's borders- is located in the Pilkhana area of Dhaka.
There has been no indication that this is a coup, says the BBC's correspondent in Dhaka, Mark Dummett, who is at the scene.
One report said that the gun battle coincided with a meeting of senior Bangladesh Rifles officers.
A government source told the BBC that a curfew would be announced.
Reports say that smoke is coming out of the complex and security forces have cordoned off the area.
Complex sealed
"There has been a huge exchange of gunfire at the headquarters. We have heard mortar fire," local police chief Nabojit Khisa told the AFP news agency.
Officials at Dhaka's Medical College Hospital said one civilian had been killed. At least six people have also been wounded, although it is not clear whether any of them are soldiers.
He said police were not being allowed to enter the complex.
A large plume of smoke can be seen rising above a conference room inside the barracks in the Pilkhana area of Dhaka, our correspondent says.
There is no information yet on casualties, but reporters say some civilians walking past the camp have been hit.
Local media reports say that is where the mutineers have locked up their officers.
TV pictures from a Dhaka hospital showed some civilians injured in the gun battle being wheeled in.
Police were not being allowed to enter the complex.
There are unconfirmed reports that soldiers have also opened fire on a helicopter patrolling above the camp, where the fighting is taking place, our correspondent says.
The government is said to have urged the mutineers to lay down their arms.
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