An Egyptian policeman and an unknown gunman were killed today in a gunfire exchange in a public area in El Arish in Northern Sinai, officials said. Security forces said that two gunmen were travelling in a motorcycle with machine guns. They were driving alongside a truck carrying money. Officials said the gunmen attempted to hijack the truck, but security guards prevented them from getting control of the vehicle. Reports show a policeman and one of the culprits were killed with three bullets Sources denied that the incident was a bank robbery attempt.  Officials confirmed it took place near a government bank, but that it was not the gunmen\'s target.