An inquiry has been ordered after at least 15 people died in a fire that broke out in a building in the northern Indian city of Lucknow on Monday.

The building housed a pet shop and an animation centre. Witnesses described people jumping from windows and climbing down cables to escape, while rescue teams broke through a wall to save lives.

The cause of the fire is yet to be ascertained. Authorities said the building lacked emergency exits and people got trapped inside as smoke spread.

The tragedy has renewed concerns about fire safety in India's densely occupied commercial buildings, with several deadly blazes in recent months exposing violations of fire safety rules.

The victims included trainees and employees who were inside the building when the fire broke out, according to officials and relatives.

"An inquiry has been initiated," Brajesh Pathak, deputy chief minister of Uttar Pradesh state, whose capital is Lucknow, told reporters. "Authorities have been directed to ensure that such incidents do not happen in the future."

The fire was reported at around 14:45 local time (09:15 GMT) on Monday in Lucknow's densely populated Aliganj area.

The pet shop was on the ground floor, while the two floors above were occupied by the animation and 3D gaming centre, officials said.

Flames and smoke engulfed the building's only staircase, cutting off the sole exit. Firefighters reached the terrace via a neighbouring building and breached a side wall to begin rescue efforts.

Witnesses described scenes of panic as people trapped inside tried to escape the smoke. Some climbed down power cables, while others jumped from windows. Several were seen calling for help from inside the building, and dozens were injured.

Anurag Ojha, who witnessed the fire, told BBC Hindi that people trapped inside were calling for help from the windows.

"I was resting in my room and there was a foul smell outside. When I looked, there was a huge fire and people were crying for help," he said, adding how people in the area started throwing stones to break the glasses of the building so that more people could escape.

Another witness, who identified himself only as Aman, told ANI news agency that local residents rushed to help after seeing smoke coming from the building.

"We rescued five or six people," he said, adding that one man jumped from the building and was seriously injured.

Several victims managed to contact relatives while trapped inside the building.

Prabhujyot Singh told BBC Hindi that his son called him during the fire and said: "Papa, there's a fire. Save me, I'm trapped inside."

But, by the time he could reach the spot, he said, it was too late.

Mohammad Shazan, 19, a trainee at the animation centre, called his family to say he was trapped. His brother told BBC Hindi that Shazan had taken refuge in a washroom to escape the smoke but was unable to get out.

Relatives of some victims said a biometric entry system controlled access to parts of the premises, making it harder for people to escape when the fire broke out.

Police have filed charges over acts causing or endangering life, and arrested four people in connection with the fire, officials said. Four public officials have also been suspended.

The Lucknow fire comes less than a month after a blaze at a bed-and-breakfast in India's capital Delhi killed several people.