Two police officers have been shot dead on a rural road in western Germany while on a routine patrol.

Two suspects were detained hours later.

The shooting happened during a traffic check near Kusel at about 4.20am local time, police in Kaiserslautern said.

The officers radioed that shots were being fired, spokesman Bernhard Christian Erfort told n-tv television.

Police officers block the access road to the scene where two police officers were shot during a traffic stop near Kusel, Germany
Police officers block the access road to the scene where two officers were shot during a traffic stop near Kusel (Thomas Frey/dpa via AP)

But reinforcements who arrived at the scene were unable to help the 24-year-old woman and 29-year-old man.

Mr Erfort said he did not know whether the officers had seen something particular about the assailants’ vehicle that they wanted to check or whether it was just a routine check.

German news agency dpa, citing unidentified security sources, said that the officers reported finding dead game in the car before the shooting started.

But what exactly happened remained unclear, as did a possible motive for the shooting.

Police called on local drivers not to pick up hitchhikers in the Kusel area as they hunted for the perpetrators there and in neighbouring Saarland state.

Later on Monday, police said they had arrested a suspect for whom they had put out a wanted notice.

The 38-year-old man from the region was apprehended in Sulzbach, about 37 kilometres (more than 20 miles) from the scene of the shooting.

Police officers prepare for an operation close to a road where two police officers were shot during a traffic stop near Kusel, Germany
Police officers prepare for an operation close to the scene of the shooting (Michael Probst/AP)

Police said he did not give any information on the case after his arrest at around 5pm local time.

A second suspect, a 32-year-old man, was also detained.

Investigators were working to determine whether he had anything to do with the shooting.

They said they were continuing to look for anyone else who may have been involved.

The younger officer killed in Monday’s incident was still studying at a police academy, the GdP police union said.

“Regardless of the motive, this crime is reminiscent of an execution and shows that the police risk their lives for our security every day,” interior minister Nancy Faeser tweeted.

She said “we will do everything” to catch the perpetrators.