Senior German officials have called for tightened gun controls after Friday's deadly shooting in Munich that claimed the lives of nine people and the gunman, an 18-year-old reportedly obsessed with mass killings.

"We must continue to do all we can to limit and strictly control access to deadly weapons," Vice-Chancellor Sigmar Gabriel, leader of the centre-left Social Democrats, told local media on Sunday.

He said authorities were investigating how Ali Sonboly, a German-Iranian who held dual citizenship, had gained access to a weapon despite signs he had significant psychological issues.

"Gun control is an important issue," he said.

Sonboly opened fire near a busy shopping mall on Friday night, killing nine people and wounding 27 others, before turning the gun on himself as police approached. The Munich shooting was the third act of violence against civilians in Western Europe in eight days.

German Interior Minister Thomas de Maiziere, a member of Chancellor Angela Merkel's conservative Christian Democrats, told Bild am Sonntag in a separate interview that he planned to review the nation's gun laws after the attack.

He said the laws were already strict, which he considered appropriate, but it was critical to understand how the shooter gained access to the pistol he used.

"We have to evaluate carefully if and where further legal changes are needed," he was quoted as saying on Sunday.