Paraguayan authorities say dozens of attackers armed with assault rifles used explosives to blast open the vault of an armored car company and then apparently escaped into Brazil with an undetermined amount of cash.

Regional police spokesman Anibal Lima says the attack on the Prosegur company began early Monday and lasted for three hours.

Authorities say at least one police officer was killed, three civilians were injured and several vehicles were burned.

Brazilian gangs are suspected of carrying out the attack in the border city of Ciudad del Este.

Lima says police believe the attackers escaped by boat.

City investigations chief Arsenio Correa says 50 to 80 people may have been involved in the attack.