Yaroslav Moskalik, a senior Russian military officer, was killed Friday when a car exploded next to him in a residential area of Balashikha, just outside Moscow. Russian authorities have arrested a suspect they say has been working with Ukrainian intelligence.

“The detainee turned out to be an agent of the Ukrainian special services, Ignat Kuzin, born in 1983, who has a residence permit in Ukraine, said Russian Investigative Committee spokeswoman Svetlana Petrenko.

Petrenko added that “investigators from the Central Investigation Directorate of the Investigative Committee are questioning the suspect to unravel the circumstances of the crime and collect evidence.”.

Moskalik was the deputy chief of the Main Operational Department of the Russian army’s General Staff. According to Russian authorities, the vehicle that exploded, a Volkswagen Golf, was parked in a densely populated area.

So far, Ukrainian authorities have not officially commented on the incident.

The strike comes a few months after the December attack, when Lieutenant-General Igor Kirillov was also killed in an explosion outside his home after an explosive device hidden in an electric scooter was triggered remotely.