A bakery worker narrowly escaped serious injury due to a chance trip to the restroom just moments before a man attacked her colleagues with a knife in a Cheung Sha Wan shopping centre on Sunday.

The woman, who works at Mr Bakery in the Hoi Lai Shopping Centre, told local media that she returned from the restroom to find her three colleagues covered in blood at about 7.30am. The attacker, she said, had come in and slashed the victims – two women and a man, aged 39 to 63 – without saying a word.

The 40-year-old suspect then fled the scene, leaving the knife on the floor, only to later turn himself in at the Cheung Sha Wan Police Station, according to a force insider.

The man, who had been receiving treatment for mental health issues for more than a decade, was agitated after making a purchase at the bakery shortly before the attack, the source said. It was after a staff member allegedly asked him whether he was crazy that he went home and returned with the knife.

The entrance to the Hoi Lai Shopping Centre in Cheung Sha Wan, where the attack occurred.

One of the female victims suffered a cut on her forehead, while the other was slashed in the face. The man, who was the baker at the shop, sustained a deep slice to his arm.

The victims were sent to the Caritas Medical Centre in the district, where one of the women remained in serious condition as of Sunday evening, according to the force. The other two victims were in stable condition.

The employee who avoided the attack told local media that none of them knew the suspect, and he was not a regular customer.

“I happened to go outside to the restroom so I escaped it,” she said.

The suspect, she added, had “forced” the two female colleagues into a small room with no way out, but the baker heard the commotion and came to their aid.

While trying to protect the two women, the baker suffered a cut so deep on his left arm that part of the bone was exposed, she said.