Indian police said Monday they had arrested a doctor and the owner of an unlicensed hospital where six newborn babies died in a fire on a crowded ward without fire exits.

The blaze broke out at the New Born Baby Care hospital in New Delhi's Vivek Vihar area late Saturday evening.

In the crucial first minutes, it was bystanders who spotted the fire and braved the blaze to rescue the newborns inside.

Vinod Sharma, who lost his day-old baby boy in the blaze, blamed the hospital authorities for the tragedy.

"He had a problem with breathing. The doctor had said that he will be fine in a few days," Sharma was quoted as saying by the Indian Express newspaper.

"We didn't know that the hospital would kill him."

Fires are common in India due to poor building practices, overcrowding and a lack of adherence to safety regulations.

Senior police officer Surendra Chaudhary told AFP that the hospital did "not have a fire exit system".

Its licence had expired in March and the owner had crammed into the ward more than twice the number of beds it previously had permission for.

"The hospital had permission for up to five beds but they had installed more than 10 beds," he said.

"In view of all this, we have made the arrests."

Five babies pulled out from the fire are still recovering in another hospital.

- 'Highly flammable' -

The blaze in the hospital on Saturday broke out just hours after a separate fire at an amusement park in India's western state of Gujarat.

The toll from that fire rose to 28 on Monday, police said.

The fire -- which ripped through a centre with a bowling alley and other games crowded with youngsters -- was triggered by welding work on the ground floor, chief fire officer Ilesh Kher told reporters.

"The CCTV footage clearly shows that a spark from the welding work fell on a stack of corrugated cardboard sheets below, causing the fire," Kher said.

"This spread very fast as the material was highly flammable."

The corpses were so badly burned they have not been identified so far.

Police have charged seven people with culpable homicide in connection to that fire.

The two fires came as northern India was gripped by intense heat, with temperatures in Delhi hitting 46.8 degrees Celsius (116.2 degrees Fahrenheit) on Saturday, according to the India Meteorological Department.