It’s a bizarre medical injury that left one man in India with the most literal version of "stabbing pains" possible.

Police constable Surjeet Singh arrived at a hospital in the northern Indian city of Amritsar with complaints of severe abdominal pain earlier this August. It didn’t take too long to figure out what had caused his distress: Singh had, over the course of two months, intentionally swallowed a total of 40 foldable knives. On Friday, August 19, doctors spent five hours surgically removing the knives, which had caused massive internal bleeding, from his stomach. They were in complete amazement at what was transpiring.

"He had a wild urge to consume metal. Even for us, the experienced surgeons, it was frightening," Dr. Jatinder Malhotra, the lead surgeon, told CNN. "We were so nervous... a small mistake could have taken the patient's life. In my 20 years of practice, I have never seen anything like it."

Indeed, when Malhotra and his colleagues looked through the medical literature, they couldn’t find a single other similar case of knife-swallowing. Singh, a 42-year-old father of two, wasn’t sure why he did what he did, aside from having developed a love for the taste of metal.

"He told us he would swallow the knives along with a glass of water," Malhotra told the Associated Press. "He had no explanation for why he did it. Just an urge."

While knife-swallowing may have been previously unheard of, the urge to eat inedible objects certainly isn’t. People who suffer from a rare eating disorder known as pica feel compelled to eat substances that contain little nutritional value, ranging from dirt to the person’s own hair and even feces. Most cases, however, happen among very young children, pregnant women, and those with other developmental conditions like autism. It’s theorized that pica may at least be partly sparked by malnutrition and mineral deficiencies.

Though Singh is recovering quickly, doctors will keep him in observation for the next few days until he is cleared by a psychiatric evaluation. For his part, he has sworn off the habit completely.

"I will never do such acts ever again," Singh told CNN. "I'm a new person now."

Read More:

'Pica,' Rare Disorder, Causes 6-Year-Old Zach To Eat Moss, Window Blinds; Gets A New Garden Because He Ate The First One. Read here.

3 Strange Eating Disorders That You May Not Have Heard Of — One Of Them Includes Eating Dirt, Chalk, Or Sand. Read here.