Doctors said a Chilean man lost two fingers and could lose vision in one eye, while a Swiss Embassy worker has serious hand injuries.
Officials blame the bombings on anarchists. Authorities said Thursday's bombs were sent from within Italy. Security officials said that an Italian group calling itself the Informal Anarchist Federation claimed responsibility.
Officials said they're also keeping a close eye on the Vatican where large crowds will be gathering for Christmas Eve and Christmas Day.
No additional devices were found on Friday.
The Associated Press contributed to this report.