Police said the victims appear to have died from inhaling poisonous fumes inside the pit, The Jakarta Post reported Wednesday.
The first worker fell into the pit when plywood sheeting covering the hole collapsed Tuesday, police said. He passed out, and a second worker who went to his rescue also fell into the pit.
Five other workers attempting rescues suffered similar fates.
Six construction workers at the site, assisted by police, removed the seven men from the pit.
Two men were found alive and were taken to a hospital, where they were listed in critical condition.
Some 2,114 workers died in 96,314 workplace accidents in Indonesia in 2011.
Charlize Theron not engaged to Sean Penn 'yet'
Pregnant Mila Kunis wins 'Best Villain' at MTV Movie Awards