Poros collided with a bridge in the northern state of Brazil Pair plunged into a plot of 200 m
Witnesses said that two little ones the cars fell into the water after the ship crashed into one of the pillars.
It is unclear, however, how many people were injured, and scuba divers looking for a river. The crew members on the vessel survived.
Governor Parade Helder Burbalo signed a state of emergency after the accident.
"Our priority is to find victims and provide full support to their families," he said.
Mr Barbalho has published frames from a 860-meter bridge destroyed on Twitter.
A bridge in the Amazon region leads to one of Brazil's most busy ports, Belen.
The authorities are working to clear garbage from the river and set up a number of barges to transfer residents through the water until it can be secured by placing warning signs on the pillars of other nearby bridges.
Local media reported that a bridge survey earlier this year revealed corrosion on the pillars. Despite the fact that the government turned to emergency funds to solve the problem, it is reportedly not considering this issue serious enough to close the route.
The police are investigating whether the ship was officially registered, reports Associated Press.
The authorities told Reuters that a collapse could affect the supply of products through the northern ports.