Eleven Western Greyhound buses at the Liskeard depot cannot leave Three buses have been destroyed in a second suspected arson attack at a Western Greyhound depot in Cornwall.
People living nearby raised the alarm after seeing the flames at the depot in Trevecca, Liskeard at about 06:30 GMT.
In May, 35 buses were written off after a severe fire in another suspected arson attack at the firm's depot in Summercourt.
Greyhound manager Mark Howarth said: "It is not as bad as the last one, but one wonders why they are doing this."
Police and Cornwall Fire and Rescue Service have both confirmed that they are treating the fire at the Liskeard depot as arson.
Buses stuck
The fire has led to disruption to services because the depot and nearby roads have been closed while investigations continue.
Eleven Western Greyhound buses, including school buses, and two Plymouth City Bus vehicles parked at the Liskeard depot cannot leave.
Buses at the depot served three routes, the 593 between Newquay and Plymouth, the 572 between Polperro and Plymouth and the 573 between Polperro and Callington.
Mr Howarth said said: "We are waiting for the all clear to get the buses out.
"We are trying to run the full 593 service with buses from Summercourt, but the 572 and 573 and related school buses won't operate until further notice."
Plymouth City Bus said that services 120 and 121 were affected, but replacement buses were on their way.
The firm tweeted: "Apologies for this disruption which is beyond our control."
Two men arrested on suspicion of arson after last year's fire at Summercourt were released on police bail.