Mumbai police on Friday brought in a person to Bandra police station for questioning in the investigation into the attack on Saif Ali Khan in which the Bollywood star was seriously injured.

The 54-year-old actor was repeatedly stabbed by an intruder in his plush apartment in the western Mumbai suburb of Bandra area early on Thursday.

Saif had a knife stuck in his thoracic spine when he was brought to Lilavati Hospital, a wound that trauma surgeons consider potentially life-threatening, depending on its depth and angle and the affected structures.

Saif received six stab injuries, including in his neck, in the attack around 2.30am on Thursday. He continues to be in the hospital.

The Mumbai police have formed 20 teams to track down and nab the intruder and are tapping their network of informers to locate him, officials have said.

The crime branch and the local police have gathered technical data, including how many mobile phones were active in the area when the actor was attacked during what the family said was a “burglary attempt” in his apartment housed in Satguru Sharan building.

Evidence has been collected from Khan’s home and the building with the help of forensic teams and the dog squad and searches were conducted at many places in Mumbai to track down the attacker.

Police are examining the CCTV footage of the building showing the intruder, who was armed with a wooden stick and a long Hexa blade, fleeing after the attack.

The footage, captured at 2.33am, clearly showed the young suspect’s face. He was seen wearing a brown T-shirt with a collar and a red scarf while scurrying down the stairs on the sixth floor of the building. The actor lives on the top floors of the 12-floor building.

Besides Khan, a 56-year-old staff nurse at the house, Eliyama Philip, who is the complainant, and a domestic help suffered blade injuries in the incident.

The entire family – Khan, his wife and fellow star Kareena Kapoor, and their two sons, four-year-old Jeh and eight-year-old Taimur – were home in the 12th-floor apartment along with their five house helps.

In a statement to the police, Jeh's nanny Philip, who first encountered the armed attacker, said he asked for Rs 1 crore.

The intruder did not force his entry or break into the actor's flat but possibly sneaked in at some point during the night with the intention of robbery, police officials said.

The man, she said, pointed a finger at her and warned her, "Koi awaaz nahin [don't make any noise].”

Hearing her scream, Khan and Kareena rushed out of their room. The intruder, who Philip said was between 35 and 40 years old, then attacked Khan with a knife.