A woman who stabbed a man in the chest during a first date had intended to cut out and eat his heart before leaving a note to warn she would kill again, authorities in the US said.

Police in Washington claimed the 24-year-old woman plotted to carry out gruesome murder at a motel in Lynnwood on Sunday night (29 January).

She allegedly told officers it was the first step of her chilling plan to become a serial killer.

The injured 29-year-old man was said to have narrowly escaped with his life after managing to flee the motel room and call the police. He was reportedly taken to hospital with a punctured left lung after being stabbed in the chest.

His alleged attacker was named by local media as Edmonds resident Amy Brown, who was arrested on suspicion of first-degree attempted murder with bail set at $1m (£790,000, €930,000).

The man said he first met the suspect online via Craigslist after he made a post seeking "friendship and possible dating", according to court documents seen by local news channel Kiro 7.

The pair met for a first date and ended up at Rodeo Inn motel on Highway 99, where they lay together on a bed and talked.

Brown was then said to have asked him several times if he was a serial killer, to which he repeatedly responded "no", before she then allegedly climbed on top of him and declared: "Well, I am a serial killer."

She then started stabbing him in the chest with a pocket knife, police said.

The alleged victim managed to push her off during a struggle, before running out of the room and calling 911 from the motel office. He said there had been no altercation or argument prior to the incident.

Brown was eventually found by attending police in the motel parking lot.

Officers said the suspect told them she was "a loon" when they asked what had happened, adding that she wanted to become a serial killer.

She allegedly went on to admit her plan in full: that she had intended to cut out and eat the victim's heart, and then leave a pre-prepared note warning police she would kill again.

An officer said in court documents: "She was extremely emotionless when she spoke to me about attempting to kill (the victim).

"At one point throughout the conversation, she was more concerned with missing work the following day than facing the possible consequences of an aggravated assault."