CHICAGO, Dec. 22 (Xinhua) -- Thirteen people at a house party were wounded on the South Side of Chicago when someone inside started shooting early Sunday morning.

All the 13 people, whose ages and conditions are not available yet, were hospitalized.

The house party in the Englewood neighborhood was held in honor of the birthday of a 22-year-old man, who was shot and killed during an attempted carjacking in Chicago's Loop Area in April, local media reported.

During the last weekend prior to Christmas holiday, at least four people have been killed and 11 others have sustained injuries in shootings across the Chicago city by Saturday, Chicago police said.

Shootings and homicides in Chicago are projected to drop by double-digit numbers for the third consecutive year, according to Chicago police data.