The bedouin have been protesting against the killing of a tribesman in a shootout with police on Monday.
Angered by the incident, bedouin launched violent protests in the peninsula, including seizing a police station.
Peaceful protests continued on Wednesday.
One protest saw the bedouin take 72 automatic rifles, 20,000 bullets as well as walkie-talkies and night-vision goggles, from another police station, in Wadi al-Azareq, north-central Sinai, a security official told the AFP news agency.
Three bedouin died and 30 policemen were wounded during Tuesday's protest at Wadi al-Azareq, the official said.
"Security forces are looking for the missing equipment," the official said.
Spate of bombings
A spate of bombings that hit popular tourist destinations in Sinai between 2004 and 2006 led to massive sweeps of the peninsula, with thousands of bedouin being arrested.
The Egyptian government has regularly promised to pump money into the impoverished north Sinai and several attempts have been made in recent months to broker a rapprochement between the authorities and the bedouin.
Bedouin say police routinely carry out arrests in north Sinai and that they feel under threat of having their car licences confiscated or homes searched at any time.
In July, the detention of one of their number in the Sinai without charge saw hundreds of bedouin burn tyres and block roads in protest.