(two) Three policemen were also reported to have been injured in the blast.
The military recently intensified a crackdown against militants in Sinai, where attacks have surged since the fall of Hosni Mubarak in 2011.
(one) Medical sources and officials said the police were in two buses which came under attack from armed men close to the town of Rafah on the Gaza border.
(four) Overnight on Saturday, the AFP news agency reported that a civilian, two soldiers and a police officer were killed in an attack in Assuit.
Egypt's interim leaders have declared a state of emergency amid the nationwide unrest which has followed the ousting of Islamist Mohammed Morsi as president.
(three) Egyptian deployments in Sinai are subject to the 1979 peace treaty between Israel and Egypt.
In Monday's incident, security sources said four armed men had stopped the police buses and forced the passengers to get out before shooting them.