Dutch police step up probe into terror scare after canceling a rock concert in Rotterdam

Dutch police stepped up their investigation Thursday into a possible terror threat, arresting another man after canceling a Rotterdam concert by a US rock group following a tip-off from Spanish authorities.

The 22-year-old was arrested in a pre-dawn raid on a house in the Brabant region, where there was "also an extensive search," police said in a statement, adding that the driver of a van with Spanish plates held late Wednesday also remained in custody.

The arrests come after twin vehicle attacks in Spain last week killed 15 people, and were claimed by ISIS.

In May, a suicide bomber killed 22 people including seven children at a concert by US singer Ariana Grande in the English city of Manchester.

"A 22-year-old man from Brabant was arrested Thursday morning in the investigation into a terrorist threat Wednesday evening in Rotterdam," Dutch police said in a statement.

It was the second arrest after the van driver was held late Wednesday in Rotterdam, only hours after officials canceled a concert planned by Californian rock group Allah-Las.

The driver, who "appeared to be under the influence of an alcoholic substance, was detained and transferred to a police facility" on Wednesday, police said, adding that officers had found a "couple of gas canisters" in his van.

The driver, who police said was a mechanic, will be interviewed again Thursday.

But Dutch authorities have cautioned there may be no link between the van driver and the terror tip-off from Spanish police.

Witness Usama Mohamed told AFP he had watched events unfold close to the Maassilo concert hall, after the van was spotted in a nearby street.

"What I saw was a vehicle with lots of gas cylinders inside," Mohamed said.

"After what happened in Barcelona, I think the police really took the situation seriously and didn't want to take any risks in Rotterdam."

Spanish police had carried out new raids Wednesday after vehicles ploughed into pedestrians on Barcelona's busy Las Ramblas boulevard and a seaside promenade in the resort town of Cambrils last week.

On Wednesday Dutch authorities decided to cancel the Allah-Las concert after a tip-off from Spanish police around 5:30 p.m.

"I was warned by telephone that we had received a threat which had implications for an American concert at the Maassilo in Rotterdam," the city's mayor, Ahmed Aboutaleb, told reporters.

"This signal came from the Spanish police to the Dutch police."

'Holy sounding' name

The four-piece band, from Los Angeles, was escorted from the concert hall by police wearing bullet-proof vests.

In a statement sent to AFP, they said they were "unharmed and are very grateful to the Rotterdam police and other responsible agencies for detecting the potential threat before anyone was hurt."

The electic band refused to comment further. In an interview with the British daily The Guardian last year, they said they receive emails from Muslims offended by their name, but "that absolutely wasn't our intention."

They said they chose to use Allah — Arabic for God — because they wanted something "holy sounding."

"We've had the name so long I don't think we can change it. That wouldn’t work."

The Netherlands has so far been spared from the slew of terror strikes which have rocked its closest European neighbors in the past few years.

But in the face of a number of scares in recent months, and reports that people linked to some of the attacks in Europe may have crossed briefly into the country, concerned top Dutch security and intelligence officials have been keeping a wary eye on events.

In June, a Dutch man — known to authorities as being possibly radicalized — was arrested filming outside one of the country's largest stadiums during a concert. He was later freed, but the incident is still under investigation.

by Jo Biddle and Sophie Mignon/AFP