There is no word yet on what caused a fire to break out Wednesday morning at the world's tallest modular building under construction near Barclays Center, according to the city fire department.

Officials said flames broke out on the seventh floor of the 32-story building at 461 Dean Street between Flatbush and 6th Avenues around 8:30 a.m.

It took about 40 minutes to get under control, and no one was hurt.

The 363 units were built off-site, and then trucked to the site to be stacked.

It is slated to be the first residential building to open at Pacific Park, formerly known as Atlantic Yards.

A spokesperson for Forest City said the building will still open in time for the fall.