Egyptian police clashed with armed men in northern Sinai's Arish, state television reported on Thursday, a day after security forces began a crackdown on Islamist militants in the region.

"Clashes resumed between armed men and police forces in front of police station number two in al-Arish," Nile News television reported, citing its correspondent there.

Masked gunmen had attacked seven army and police checkpoints in Arish early Wednesday morning.

The assaults came after the Sunday night attack on a checkpoint in Rafah near the Israeli border by gunmen believed to belong to extremist Islamic groups, killing 16 Egyptian soldiers.

Egyptian military and security forces strengthened their presence in Sinai after the incident and carried out a military campaign Wednesday morning that officials said killed 20 militants, according to Reuters.

State media outlets said Thursday that military reinforcements were sent to Rafah.

Residents told state-run paper Al-Ahram they have not witnessed such military mobilization since the 1973 war between Egypt and Israel. According to Al-Ahram, the reinforcements included more than 35 armored vehicles, 60 tanks, and 13 personnel carriers.

A fleet of armored vehicles and personnel carriers arrived in Arish on its way to other parts of Sinai and the road between Arish and Rafah.

Eyewitness said the convoy was greeted with chants from bystanders, according to state news.