Eight people have died in an apartment block fire in Paris.

Police have detained a man amid suspicions that the blaze, at the foot of the famed Montmartre hill, was started intentionally, officials said.

Some people died leaping out of windows to flee what appeared to be the deadliest blaze in the French capital in a decade. The dead included two children.

Four survivors were taken to hospital, said interior ministry spokesman Pierre-Henry Brandet.

Firefighters extinguished a small paper fire around midnight in the building, then were called back two hours later for a much bigger blaze, fire department spokesman Gabriel Plus said.

When the firefighters returned, Mr Plus said they were “immediately confronted with a disaster of an exceptional scale”.

People screamed for help from inside the building, several windows were blown out, and two people who had already jumped from windows were on the ground motionless, he said.

Mr Brandet said the fire began in a ground floor stairwell. Mr Plus said it quickly engulfed all five floors of the building and consumed several apartments and the stairwell, forcing people to flee out of windows.

More than 100 firefighters were required to extinguish the blaze.

“I was sleeping and I heard cries of people calling for help,” said Florent, who lives in a different entrance of the same building.

“I opened the door to see the damage ... and I went to get a bucket of water in the panic. Then I reflected and thought the flames were too big to stop them by myself,” and instead called the fire department, he said.

A man was detained on suspicion of involvement in the fire, the Paris prosecutor's office said. French President Francois Hollande issued a statement promising all necessary efforts “to shed light on the drama”.

Paris mayor Anne Hidalgo, asked whether it could have been prompted by electrical or gas problems, said the building had not had any previous problems and had been in good condition.

It was one of the deadliest fires in Paris since a 2005 fire in a hotel housing African immigrants that left 24 people dead, including 11 children.