BOGOTA, Dec. 29 (Xinhua) -- At least 31 people have been injured in an explosion at a nightclub in northern Colombia after a grenade was allegedly thrown into the crowd, local authorities said on Friday.

The explosion rocked the Bora Bora nightclub early Friday in the municipality of Caucasia in the department of Antioquia when dozens of people were at the club, Caucasia Mayor Oscar Anibal Suarez said in a statement to local media.

The mayor confirmed that local police have captured two suspects -- a man and a woman -- for throwing the grenade.

The injured people have been transferred to local hospitals in the region, according to local health authorities.