BERLIN (AP) — An Iraqi-born man deliberately drove his car into motorcycles along a stretch of Berlin highway, leaving at least one person in life-threatening condition in what German officials said Wednesday was a terror attack.

“According to the current state of our investigation we assume this was an Islamist-motivated attack,” Berlin's senator for the interior, Andreas Geisel, said. “A religiously motivated background cannot be excluded.”

Six people were injured, three of them severely, when the 30-year-old man allegedly drove into several vehicles, intentionally hitting motorcycles, on Tuesday evening, Berlin prosecutors and police said in a joint statement.

The crashes at three different locations happened during rush hour on the BAB100 highway shortly before 7 p.m. local time and led to a complete closure of one of the main traffic arteries of Berlin.

Investigators did not reveal the man's identity, as is customary in Germany, but local media identified the suspect as Sarmad D. He is being investigated for three cases of attempted murder.

There were also indications that the man had mental health issues.

“The fact that the suspect was possibly suffering from psychological problems does not make this issue any easier,” Geisel said. “If personal problems mix with religiously loaded ideas, this can lead to uncontrollable acts — yesterday's events have shown in a very painful way how vulnerable our society is.”

Prosecutor Martin Steltner told reporters they were investigating if the suspect was linked to any terrorist group or if other people were involved in the attack but had not found any indications of that yet.

However, investigators were looking into tips that the man may had possible contacts with other extremists, Steltner added.

The suspect, who was driving a black Opel Astra, stopped on the highway after the third crash and put an old ammunition box on the roof of his car, claiming it had explosives inside, the statement said.

Several media reported that the man shouted “allahu akbar” or “God is great” as he got out of his car. The Bild daily reported that he also shouted: “Nobody gets closer, or you will all die.”

The suspect then rolled out a prayer carpet and started praying, daily paper Tagesspiegel reported. A police officer of Arabic immigrant background then approached the man, talked to him in Arabic, pulled him away from the car and detained him, the paper reported.

According to Tagesspiegel, the man is known to Berlin police. He was born in Baghdad in 1990 and lived in a refugee home in Berlin. In 2018, he was detained for injuring others and taken to a mental institution for a short time, Tagesspiegel reported.

Dpa reported that the suspect allegedly made references to his plans on Facebook before the attack. He posted photos of the car that he later used in the attack, as well as religious writings, it said.

After the man was detained, hundreds of people stuck on the highway nearby were led away from their cars. Specialists opened the box with a strong jet of water but found only tools inside.

Among the three severely injured people, one is in life-threatening condition with severe head and back injuries, Steltner said. One of the three was a firefighter going home from work.

“If a car intentionally targets motorcycles, they don't have a chance,” Geisel said.

The suspect first hit a car on the highway in the Wilmersdorf neighborhood, then drove into a motorcyclist, leaving him behind with life-threatening injuries. He hit a second person on a motor scooter, and eventually used his car to push a third motorcyclist into the front of another car, prosecutor Steltner said. The suspect finally got out of his car near the Alboinstrasse exit in Berlin's Tempelhof district.

The incident led to long traffic jams Tuesday evening. The people who were led away from the site where the suspect was detained and others who were stuck on the highway for hours were getting support from the German Red Cross, the Berlin fire department tweeted Tuesday night.