NEW DELHI: A former army lieutenant bludgeoned six people to death with an iron rod Tuesday in a killing spree that sparked panic in a northern Indian city.

Naresh Dhankar, 45, began his murderous rampage in a hospital in Palwal then walked the city's streets picking victims at random, police said.

Three watchmen were among those who died in the attacks.

"He attacked a woman at a hospital first. We rushed there and as we were scanning the CCTV footage we got to know that more bodies had been found," said police spokesman Sanjay Kumar.

"The accused has been arrested and is currently undergoing treatment at a hospital," the spokesman told AFP.

A TV grab showed Dhankar, wearing a blue pullover, walking with an iron rod in his hands.

As news of the attacks spread on social media, police appealed to residents of the city in Haryana state not to panic.

Kumar quoted Dhankar's wife as saying he had been "mentally disturbed" for the past few days.

"We are investigating to find out the exact motive behind the killings," the spokesman said.