The blasts are the second attack on the French island in just under a week.
On Tuesday two bombs went off outside a government office and police headquarters, injuring one person.
There have been no claims of responsibility for either set of attacks, police said.
Police had been on alert for violence from Corsican separatists since the sentencing earlier this month of Yvan Colonna, 47, for killing Claude Erignac, the state-appointed prefect or governor of Corsica, in February 1998.
The French Mediterranean island regularly faces small-scale bombings, often waged by separatists targeting government buildings and holiday homes.
The blasts normally occur near empty buildings.
"We have the impression that there is ... an escalation of the violence," Christian Leyrit, the national government's administrator in Corsica, told local LCI television.