At least eight people were killed and more than 20 others wounded when gunmen opened fire at a disco in Villa Nueva, a city in the southern part of the Guatemala City metropolitan area, authorities said.
Three unidentified men were pronounced dead at the scene.
The gunmen opened fire around midnight at the El Ranchon nightclub in Villa Nueva, a high-crime area, a National Civilian Police, or PNC, spokesperson said Sunday.
"There are more than 20 people with gunshot wounds as a result of this attack," the spokesperson said.
The wounded are being treated at Guatemala City's Roosevelt Hospital.
Investigators found five M-16 assault rifles and dozens of bullet casings at the crime scene, as well as the taxi used by the gunmen to reach the disco.
Villa Nueva, which is home to nearly 1 million people, has been plagued by crime for years due to the presence of street gangs that have carved out chunks of the city as their turf.
This is the first mass murder to occur since President Otto Perez Molina took office earlier this month, vowing to use an "iron hand" and the army to deal with crime.
An average of 16 murders per day, according to official figures, occurred in 2011 in Guatemala, making the country one of the most violent in Latin America.
Officials have blamed youth gangs and drug traffickers for the uptick in violence.