And the government's radio service said smoke was billowing from police headquarters in the capital, Port-of-Spain, after the rebels tried to blow it up.
Dennis McComie, announcer for another station, Radio 610, said there were several explosions at police headquarters that he assumed were caused by burning ammunition.
No one was trying to put the fire out, he added, and it was spreading.
Although there were also reports of gunfire in the streets of Port-of- Spain, it was not clear if the army, police or any other group was actively opposing the coup attempt.
Abu Bakr, head of a group called Muslim Meen, announced the uprising around 6 p.m. last night on the state-run television station in Port-of-Spain. He said his group took over the Parliament building and captured Prime Minister Robinson and his cabinet.
"As of this moment, the elected government is toppled," Bakr said. As he spoke, he was sitting next to an armed man dressed in army fatigues.
"We are asking people not to be involved in any looting or they will pay the cost," he added.
Bakr appeared on televison again later in the evening and said he staged the uprising because of the "continued destitution" of the country.
He said the government's announcement earlier this week of plans to build an expensive monument in honor of a former public servant was intolerable.
Trinidad and Tobago's ambassador to the United States told CBS Radio that Robinson and the entire cabinet were in rebel custody.
James Fadelle, a Trinidadian who now lives in Miami, said he spoke with a friend in Port-of-Spain by telephone earlier last evening. He said the friend told him that some civilians were killed in the downtown area, two police stations were blown up and people were staying at home - afraid to go out.
Other witnesses told Reuters that sporadic gunshots could be heard in the streets outside the police headquarters and near Parliament, where lawmakers were meeting for a debate when the uprising began.
Young men dressed in dark clothes and carrying rifles were seen running through the streets near Parliament and shouting at pedestrians to get out of the way.
The Muslim Meen claims to have 200 to 250 members and is a tiny fringe group within the local Muslim population. The group has some ties to Libya and is said to get some Libyan financial aid.
The leader, Bakr, is a former police officer in Trinidad. Little is known about him, but some published reports in Trinidad say he spent some time in Libya.
In the last year, Bakr's group has been involved in an argument with Robinson's government over land on which the Muslims tried to build a new school.
The incident triggered a court case that ended this week with the Muslim Meen being told it was illegally occupying the land.
Trinidad, the larger of the two islands in the nation of Trinidad and Tobago, has a population of about 1.3 million, and is just off the northeast coast of Venezuela.
The former British colony gained independence in 1962. People of African and Indian descent are the largest ethnic groups.
About a third of the people are Roman Catholic and a quarter are Hindus. About 6 percent are Muslim.