BERLIN — A knife-wielding man killed one person and injured three on Tuesday at a commuter railway station in southern Germany, but investigators found no immediate evidence that the assailant had ties to known militant cells and said he would undergo psychological tests.

Authorities said the suspect, a 27-year-old German, had yelled comments suggesting ties to Islamist factions, including ‘‘infidel, you must die,’’ during the attacks in the Bavarian town of Grafing, about 25 miles southeast of Munich.

Lothar Köhler, a spokesman for the Bavarian Office of Criminal Investigation, told reporters that there was no evidence linking the attacker to Islamist militant networks or suggesting that ‘‘he was radicalized or incited’’ by videos or other sources.

The attacker has received psychiatric treatment in the past and told police he was under the influence of drugs at the time of the attack, investigators said. Köhler added, however, that the motive for the attack remains unclear.

Prosecutor Ken Heidenreich said that the suspect was scheduled to be arraigned Wednesday and that a psychological examination would be carried out to establish whether he could be held criminally responsible. Authorities would then decide whether to issue an arrest warrant or temporarily hospitalize him.

The victims were between ages 43 and 58. A 56-year-old man died from his injuries shortly after arriving at a hospital.

Washington Post