Police in Hanoi said Monday they have detained a worker they suspect may have started a fire at a confectionery factory in Hoai Duc District that killed eight people on Saturday.
Kieu Tien Vinh has been blamed for setting fire to a styrofoam ceiling while he was welding.
Factory owners Nguyen Van Duoc, 26, and his wife have also been summoned for questioning.
The fire lasted for three hours and destroyed the entire 170-square-meter (1,830-square-foot) factory. Two more victims are being treated for severe burns.
A worker who escaped from the fire told police that the only entrance to the building collapsed, leaving those remaining inside no choice but to stay still and wait for help. Their burnt remains were later found embracing each other.
The factory, which produced cakes and chocolate, was built by Nguyen Van Duoc and housed his family and workers.