The two held were found with a gun when passenger bus was searched on the Dhaka-Chittagong Highway in Tirchar area under Chandina Upazila in Comilla on Thursday afternoon.
The arrestees are Nur Hossain, 40, son of Tayeeb Ali of Ramsing village under Sadar Upazila of Munshiganj district and Jahangir Alam, 38, son of Gani Ahmed of Langolmura village of Chhagolnaiya upazila of Feni district.
Sergeant Monirul Islam of Iliatganj camp of highway police said they acted on a tip and found a Japanese 7.62mm pistol on the two.
So far the arrestees are suspected to be arms traders.
A case would be filed with Chandina police, the sergeant said.