The 32-year-old will remain in custody, suspected of attempted murder and bodily harm as well as a traffic offence, Frankfurt prosecutors told AFP.

Earlier Tuesday, the investigators had said in a statement that their probe into the motive for the unnamed suspect's act was “ongoing” and they were “pursuing all leads”. Prosecutors said the suspect was not believed to have used a weapon in the hijacking.

READ ALSO: German police probe terrorist motive in hijacked truck case

The truck sped into the parked cars a few metres (yards) away and came to a stop on the central reservation of a six-lane road.

When the man behind the wheel of the truck emerged from the crash, several
passers-by provided first aid, FNP said.

“The passers-by said the driver said 'Allah' several times” and spoke Arabic, FNP reported.

The scene of the crash. Photo: DPA

Police did not confirm this account.

Bettina Yeisley from Limburg, whose office is next to the crash scene, told FNP she heard a loud bang and ran out onto the street with colleagues.

They found the driver sitting by the roadside in the city of 35,000 about an hour's drive from the financial capital Frankfurt.

“He was bleeding from the nose, his hands were bloody, his trousers torn. He said that everything hurt. I asked him his name and he said, 'My name is Mohammed'.”

The Office for the Protection of the Constitution, Germany's domestic security watchdog, warned in April of an estimated 2,240 Islamists with “terrorist potential” living in Germany.

The far-right Alternative for Germany party has seized on Chancellor Angela Merkel's decision to leave the German border open to more than one million migrants and refugees in 2015-16, accusing her government of compromising national security.

It is now the biggest opposition party in parliament.