An engineer and a contractor, associated with the Reliance group, were shot dead in the city Monday, police said.

Sanjiv Kumar, an engineer with the Reliance goup and Ravi Ranjan, a contractor, were shot dead by unidentified gunmen riding a motorcycle in the busy residential locality of Kankarbagh, the city's superintendent of police Rakesh Rathi said.

Preliminary investigations led police to suspect a contract dispute behind the killing.

"As both the engineer and the contractor were from the Reliance group, we strongly suspect that a dispute over some contract or refusal to pay extortion might be the motive," Rathi said.

He said the armed criminals also fired at Kamlesh, a doctor who was travelling in another car, as they mistook him for a Reliance engineer. The doctor has been admitted to a nearby private nursing home in serious condition.

The double murder sent shockwaves across the city and shopkeepers in Kankarbagh closed their shops. Some agitated people also blocked roads to protest the killing.