Two youths were charged after Waterloo Regional Police received a call about the pair having potentially dangerous weapons.
On Sunday, officers were told two youths from Cambridge were in possession of firearms.
The Emergency Response Team went to a home on Elgin Street South and arrested them on Monday.
Police have not release their ages nor have they specified what guns were seized.
The pair have been charged with unauthorized possession of a firearm, possession of a weapon for a dangerous purpose and careless storage of a firearm.
Police said additional charges are also expected.