Young migrants caused panic on the Vienna subway by chanting “Allahu Akbar” and waving around airsoft guns until a passenger intervened.

The incident occurred at 2pm Monday afternoon on the Vienna u-bahn, the city’s subway system. According to witnesses, the group of four young migrants began shouting “Allahu Akbar” at the Schweglerstrasse station on the U3 line. The migrants also shouted phrases in Arabic at the frightened passengers as they waved around their airsoft guns, Kronen Zeitung reports.

One of the witnesses was terror expert Amer Albayati who told the Austrian paper the migrant teens fired their airsoft guns on the subway car. As the teens screamed in Arabic, he said most passengers fled but one man did not. Mr. Albayati said that the man tried to overpower the migrants and get them off the train.

The migrants eventually got off the train at the Zieglergasse station two stops on the U3 line away from where the incident had begun. Several witnesses used their smartphones to photograph the teens as they got off the train. The four young people are currently being searched for by authorities and may face charges.

Daniel Amann, a spokesman for Wiener Linien, the state-run company that runs the public transportation system in the Austrian capital, said: “We have safety precautions on the train and on the platforms for precisely those incidents where passengers are not feeling secure”.

The incident comes only a week after the arrest of a 17-year-old who Vienna police say was plotting a terror attack in Vienna on behalf of Islamic State. Police say that the Albanian-born teen, known as Lorenz K., had travelled to the German town of Neuss where he was in contact with another Islamic State sympathiser.

German authorities later arrested a man believed to be in contact with the 17-year-old who was also plotting a terror attack. They claim the 21-year-old had experimented with bomb making alongside Lorenz who had visited him and planned to target soldiers and police.

In a separate case, Austrian authorities raided several properties in Graz and Vienna and took down a radical Islamist group who they say were plotting to overthrow the Austrian government and install an Islamic caliphate. Eight hundred police took part in the raids which were the culmination of an investigation that began in 2015. Fourteen radical Islamists were arrested, among them several women and several Islamic preachers.