BEIRUT, Lebanon — Lebanese security officials said at least one person was killed and 28 others wounded when an explosion ripped through an apartment building in the northern city of Tripoli.

The security officials said the explosion early Saturday was caused by a bomb placed in the first floor of a building in a district whose Sunni Muslim residents support the government. The officials spoke on condition of anonymity because they were not allowed to speak to the media.

The explosion happened in an area that was the scene of fierce sectarian fighting last week between government and opposition supporters. Nine people were killed and 44 others were wounded in those clashes.