A blast has ripped through a fast food restaurant next to a busy subway station in Chile's capital.
At least 14 people were injured in the most damaging of nearly 30 bombings or attempted bombings in Santiago this year.
While no group claimed responsibility for the blast, many past bombings have been claimed by anarchist groups and Chile's government said it would invoke the country's tough anti-terror laws.
The explosion took place yesterday lunchtime at a restaurant in a small, underground shopping centre connected to the Escuela Militar subway station in Santiago's affluent Las Condes neighbourhood.
Witnesses described a gory and chaotic scene as the blast sent bodies flying, while commuters ran away from the smoke screaming.
"We heard the blast and ran in fear. When I turned around I saw the heartbreaking scene: there was glass, dust and twisted metal everywhere," Silvana Bobadilla, a waitress at one of the nearby restaurants, told local television.
The injuries apparently were caused by fragments from a fire extinguisher filled with gunpowder that detonated in a trash bin, said fire department Commander Ivo Zuvic Garcia.
President Michelle Bachelet called it an abominable act of terrorism.
"That's why we're going to use the full force of justice, including invoking the anti-terrorist law," Ms Bachelet said.
The anti-terror law enacted during Chile's 1973-90 dictatorship lets suspects be held in isolation without charges and permits the use of phone taps and secret witnesses in investigations.
At least 14 people were injured in the attack, according to a list released by local hospitals. The government's emergency medical service said that among those hurt in the blast was a cleaning woman who lost a finger.
Santiago is one of the safest capitals in Latin America, but Chileans have been shocked by at least 29 bombs that have been found across the city so far this year. Some have not gone off and none of the other bombs before this one caused any injuries.
In some cases anarchist groups have said the bombs were planted to demand freedom for two Chilean anarchists imprisoned in Spain for an explosion in a cathedral in Zaragoza last year.
Christian Toledo, the prosecutor investigating the blasts, said the explosive device used in the latest bomb was similar to the ones used in the nearly three dozen planted so far this year.
Undersecretary of the interior Mahmud Aleuy said two suspects believed to have planted the explosive device escaped in a car.
The latest blast occurred near the country's top military academy. It comes three days before the 41st anniversary of the Chilean military coup that ousted socialist president Salvador Allende and began the brutal dictatorship of General Augusto Pinochet.
Chileans remain divided over Pinochet's 17-year rule, and violent protests and clashes with police often coincide with the coup's anniversary.
Anti-riot police, firefighters and bomb squad officers briefly closed the subway station after the explosion, but it was partly reopened about an hour later.
A bomb was planted at another subway station in Santiago earlier this year causing material damage but no injuries.