French police say a deadly fire that engulfed a high-rise apartment block was deliberately lit.

Ten people have been killed and at least 30 others injured in the inferno.

Six firefighters are among the injured.

Some residents could be seen clambering across balconies in their desperate escapes.

Police prosecutor Remy Heitz says a woman is in custody on suspicion of starting the blaze.

“One person who lives in the building has been arrested — a woman aged 40 who has psychiatric problems,” he said.

“She was arrested on the road immediately after the fire was started.

“She’s under surveillance and investigations are underway to determine how the fire spread and how it was started.”

The fire started on the second floor of the building shortly after midnight.