Police officers control the perimeter outside the Paris police headquarters, Thursday, Oct.3, 2019 in Paris. An administrator armed with a knife attacked officers inside Paris police headquarters Thursday, killing at least four before he was fatally shot, officials said. (AP Photo/Michel Euler)

PARIS (AP) — France's interior minister acknowledges there were "malfunctions" that failed to prevent a deadly attack inside Paris police headquarters by a police employee.

Christophe Castaner said Sunday the attacker was a "well-rated" police employee and had "no indication of radicalization" in his internal police file. The attacker was killed after stabbing four people to death.

The Paris prosecutor says the attacker was likely in contact with members of an ultra-conservative Islamic movement.

Speaking on TF1 television, Castaner said "clearly there were malfunctions," without elaborating. He said the attacker had an "altercation" with colleagues earlier about the deadly 2015 Islamic extremist attack on satirical newspaper Charlie Hebdo, but his colleagues didn't press for any action against him.

Castaner also dismissed calls for his resignation over the slayings.

Paris prosecutor Jean-François Ricard gives a press conference at the Paris courthouse, France, Saturday Oct. 5, 2019. French prosecutors opened an investigation Friday that treats the fatal knife attack that a civilian employee carried out at Paris police headquarters as a potential act of terrorism. The longtime police employee stabbed four colleagues to death Thursday before he was shot and killed.  (AP Photo/Rafael Yaghobzadeh)
People walk out the police headquarters in Paris, Friday, Oct. 4, 2019. The French government says there is nothing to suggest the police employee who stabbed four colleagues to death at Paris police headquarters yesterday was radicalized. (AP Photo/Michel Euler)