The drivers, whose identities have not been disclosed, also had their driving licenses suspended for two months.
The traffic police acted after a video uploaded on social networks showed two buses carrying workers of South Korean company Doosan Vina obstructing the fire truck on Highway 1A despite its wailing siren last Saturday.
The truck was on its way to put out a blaze at a mattress warehouse in Binh Son District.
The two drivers owned up to their mistake, blaming "lack of observation and concentration" for it.
Doosan Vina, a subsidiary of Doosan Heavy Industries Group, said in statement it had asked its transport contractor to sack the two drivers, aged 43 and 45, for obstructing the fire truck.
Many road users in Vietnam ignore the rule that they have to give way to ambulances and fire engines.
Vietnamese laws stipulate that those failing to give way to emergency vehicles are fined VND3-5 million.