"A man stormed in mumbling something and attacked and injured two officers," SIS spokeswoman Julija Antanaitienė told BNS, adding that the attacker was apparently mentally unstable but it would have to be confirmed by doctors.
SIS head Saulius Urbanavičius later told journalists the two officers sustained leg injuries. They were taken to hospital. There's no information about the state of their health.
The identity of the attacker, aged 35-40, has been established. He also sustained an arm injury during the incident.
Kęstutis Lančinskas, head of Vilnius police, said the attacker was taken to hospital but was soon taken to a police commissariat. The man is known to the police for previously visiting other public institutions with unclear demands.
The attacker was detained by local staff and handed over to police officers.
The SIS building is currently cordoned off and guarded by police officers. Blood stains are visible near the entrance.