Bus stop shooting linked to Washington sniper

US detectives investigating the Washington sniper are attending the scene of a shooting at bus stop on a major road in Maryland.

The shots were fired at 6am local time and the style of the attack is reportedly very similar to several others in the Washington DC suburbs.

The latest shooting in Montgomery County is not far from where five sniper attacks have taken place.

Authorities say it's too early to tell if the incident is connected to the sniper who has killed nine people and injured three this month.

Montgomery County Fire Department spokesman Pete Piringer says a man suffered a chest wound and was taken to hospital by helicopter.

Police are carrying out a detailed search of the area, clogging traffic on one of the main arteries into Washington DC during the morning rush hour.

The victim was taken to a nearby hospital, authorities said.

His condition was not known.

Police put a widespread dragnet into place immediately after the shooting, clogging traffic on one of the main roads into Washington DC as the morning commute began.

Yesterday police issued a public appeal for the person they believe to be the killer to “call back.”

Montgomery County Police Chief Charles Moose, who is leading the hunt, confirmed that a message had been received from someone of high interest to investigators, but that the call was somehow muddled.

“The person you called could not hear everything you said. The audio was unclear and we want to get it right. Call us back so that we can clearly understand,” Mr Moose said.

Police said two men detained in a swoop in Richmond, Virginia, yesterday and questioned in connection with the sniper attacks had nothing to do with the case.

The men, from Mexico and Guatemala, are expected to be deported from the US for immigration violations.

Attempts to establish a dialogue with the sniper began after he left a letter for police at the scene of his latest confirmed attack in Ashland, Virginia, in which a 37-year-old man was seriously wounded on Saturday night.

The victim was shot in the stomach after leaving a restaurant with his wife.

It was the furthest from Washington the sniper has yet struck, and his first shooting at a weekend.

Hospital staff said the victim remained in critical condition. Doctors succeeded in removing the bullet during surgery.

The message left after the shooting was apparently the sniper’s second attempt to make contact with the authorities.

A tarot death card was found on October 7 outside a school where the sniper wounded a 13-year-old boy. It had the words “Dear Policeman, I am God” written on it.