SAN MIGUEL DE ALLENDE, Mexico — The Jamaican government declared a state of emergency in portions of Kingston, the capital, on Sunday after supporters of a gang leader who is wanted in the United States on gun and drug charges attacked three police stations in an attempt to pressure the government to let him remain free, officials said.

In the western Kingston neighborhood where the gang leader, Christopher Coke, is holed up, residents set up barricades and exchanged gunfire with the police. The Daily Gleaner reported that gunmen allied with Mr. Coke, who is commonly known as Dudus, were roaming the streets with high-powered rifles.

Amid growing unrest, the government met in an emergency session to try to keep the lawlessness from spinning out of control. The authorities, who said other gangs appeared to be coming to Mr. Coke’s aid, called on him to turn himself in for a hearing on extradition to the United States.

“The police are publicly calling on Christopher Coke, otherwise called ‘Dudus,’ ‘Short Man’ and ‘President,’ to hand himself over,” a police statement said. “The security forces wish to make it very clear that they view the barricading as an act of cowardice on the part of selfish criminal elements, mainly Mr. Coke.”