Teenagers arrested for allegedly plotting terror attack

German authorities have arrested four teenagers on suspicion of plotting a deadly Islamist terrorist attack in the western German state of North Rhine Westphalia, prosecutors said on Friday.

The state's Central Office for the Prosecution of Terrorism sought an arrest warrant for the teens over the Easter holiday.

They are suspected of plotting a terrorist attack "in accordance with the aims and ideology of [extremist terror group] Islamic State."

Three of the suspects are from North Rhine Westphalia, according to the state's interior minister, Herbert Reul: a 15-year-old girl from Dusseldorf, a 15-year-old boy from the town of Lippstadt and a 16-year-old girl from the city of Iserlohn.

The fourth is a 16-year-old boy from the town of Ostfildern in south-western Germany.

Reul said police first became aware of the 16-year-old girl from Iserlohn because there were indications that she wanted to leave the country to join the so-called Islamic State and fight in its ranks.

She reportedly discussed her plans on the phone with the girl from Dusseldorf, according to Reul. When searching their mobile phones, the investigators then came across a second chat in which the alleged attack plans were discussed.

According to the investigation, the 15-year-old boy from Lippstadt appeared to be the driving force in the discussions.

"Only five days passed from first becoming aware of the case to the final arrest," said Reul.

He expressed gratitude that authorities had thwarted the alleged plot so quickly, but said he was alarmed and concerned about the young age of the suspects.

"The internet certainly played a role in their radicalization. Social media and internet consumption is perhaps also one of the reasons why child and youth crime is on the rise," Reul said.

Security sources told dpa that the young people had formed the chat group, but had not drawn up a concrete attack plan for a particular time and place.

However, sources said that the cities of Dortmund, Dusseldorf and Cologne were discussed as targets, and attacks with knives and Molotov cocktails on people in churches or police officers in police stations had been considered.

Reul also said the suspects had discussed attacks on churches and synagogues in Iserlohn, as well as a potential attack in the nearby city of Hagen.

Security sources told dpa that authorities had also conducted searches as part of the investigation. A machete and a dagger were seized in Dusseldorf, but no evidence of the construction of incendiary devices was discovered.

"Instruments were found that can be used to kill people," said Reul.

Sources said that the father of the Dusseldorf suspect had already attracted attention from authorities in the past because he had allegedly collected donations for the Islamic State.

The investigators declined to reveal how the suspected terrorists were tracked down, but said that foreign intelligence agencies "did not play a role."