A group of teenagers practicing for a dance and music show were among seven Indonesians killed Monday when the building they were in collapsed, police said.
The accident happened in Cirebon, about 220 kilometres east of Jakarta.
A tall warehouse next door collapsed and then crushed the local art centre where the junior high school students were preparing for a show, according to police.
"A nine-metre tall building...suddenly collapsed onto the art centre right next to it," local police chief Trunoyudo Wisnu Andiko told AFP.
"The art centre also collapsed immediately and buried some children."
Authorities initially said just one part of the warehouse had fallen onto the art centre.
Seven were killed as the art centre caved in, including six boys between 13 and 15 years-old and the centre's 48-year-old manager, police said.
Two 13-year-old girls were also injured, with one in a critical condition, they added.
The art centre had been operating since around the 1940s.
"The building is very old, but we still need to ask experts to determine the cause of the collapse," local police spokesman Trunoyudo Wisnu Andiko told AFP.
Lax construction standards have raised widespread concerns about building safety in Indonesia.
In January, at least 75 people were injured when a mezzanine floor at Indonesia's stock exchange building in Jakarta collapsed into the lobby.
In February, the government temporarily halted all elevated transportation projects in Indonesia, after a dozen major accidents killed five and injured dozens more.