The hostage-taker shot and wounded a security guard in the building where he held a group of around 40 employees working the late shift at a call center on the fifth floor, the Emisoras Unidas radio station said. He threatened to set off a bomb he claimed he was carrying, the station said.

According to a police officer the 29-year-old assailant had a "sentimental" problem related to his ex-wife.

"It's very worrying particularly for my mother who is terrified," said Marco Ayala, whose brother Luis was being held hostage.

Fire trucks and ambulances waited outside a police cordon thrown up around the building as dozens of residents from nearby looked on.

Police delivered boxes of pizzas and bottles of water to the building.

Agencies