German police

Another user in the dark web - a hidden part of the internet where guns, drugs and child abuse images are traded - alerted police, a spokesperson said.

The boy's body was subsequently found in the cellar of a house in Herne, North Rhine-Westphalia.

Police say the 19-year-old suspect may be armed.

Searches are being carried out in towns near Herne, which lies in the Ruhr area, a heavily industrialised region.

Reports say the suspect, who is on the run, is a martial arts enthusiast.

Three people were injured, one seriously, Mannheim police said. After driving his car into the group, the suspect tried to flee the scene and was then shot by officers. The suspect was seriously injured and taken to the hospital.

No motive is known, and the suspect has not been identified.

The crash occurred near a bakery stand in a central square of Heidelberg, police said.

The Mannheim police are leading the investigation since its police district merged with that of nearby Heidelberg.

"Tired but overjoyed: we captured the terror suspect last night in Leipzig," the police said in a tweet.

The police had been looking for the suspect, Syrian refugee Jaber al-Bakr, after raiding a flat in the nearby city of Chemnitz on Saturday.

Several hundred grams of "highly volatile" explosives were found at the property, investigators said.

About 100 people were evacuated from the block of flats as the explosives were moved for a controlled detonation.

He was named by police as Jaber Albakr. He was born Jan. 10, 1994 and is from the Damascus countryside, police said.

The details emerged during a large-scale police operation in the city of Chemnitz.

Two people were arrested at the city's train station, police said, and their luggage was being searched. The station was temporarily cordoned off, police said. Another person was arrested in the city center. Police said they believe the person was in contact with the suspect.

The co-ordinated raids on 60 addresses were the first time the authorities had acted on this issue in such a way.

The aim is to tackle what police called "a substantial rise in verbal radicalism".

Typical crimes included "glorification of Nazism [and] xenophobic, anti-Semitic and other right-wing extremism", they said.