Vaud cantonal police spokesman Jean-Christophe Sauterel told the Swiss news agency sda up to 50 officers with dogs were involved in the search.
Border guards and the French Gendarmerie have been alerted.
No one was injured in the breakout that occurred at 7.35 pm after two accomplices broke through the perimeter wall in two cars, firing shots from automatic weapons.
According to police, the accomplices then helped the inmates flee over a security fence using ladders they had brought. The four men made off in one of the two vehicles, setting fire to the other.
The escapees were doing time for abduction, robbery, money laundering and arson, the police said.
One of the two is said to be a 52-year-old Swiss man, and the other is a 34-year-old Bosnian. Both were serving terms of around seven years.
The Bosnian is reported to be a member of the band of jewellery thieves known as the Pink Panthers.
Last year there were two breakouts from the La Croisée penitentiary in Orbe, raising questions about prison security. And in May this year five inmates escaped from a prison near Lausanne, also in the canton of Vaud.