Landslides and flooding triggered by heavy rainfall have killed at least 18 people in a tourist town in the hills above Rio de Janeiro, Brazilian firefighters said.

"So far, 18 deaths caused by landslides and floods have been confirmed" in recent hours, the Rio de Janeiro Fire Department said in a statement late on Tuesday.

It said more than 180 firefighters were at the scene in the picturesque hill town where Brazil's last emperor Pedro II is buried, 68 kilometres north of the city of Rio.

The department said the area got just over 10 inches of rain within three hours during the day — almost as much as during the previous 30 days combined.

'High number of incidents and victims'

Footage posted on social media showed cars and houses being dragged away by landslides and water swirling through the city of Petropolis and neighbouring districts.

Petropolis' city hall said in a statement that the heavy rains left "a high number of incidents and victims" and that rescue and recovery efforts were continuing.

Brazilian President Jair Bolsonaro, who is on a trip to Russia, said on Twitter that he instructed his ministers to deliver immediate support to the afflicted.

"May God comfort the family members of the victims," he wrote.