An Associated Press reporter heard two explosions from the Egyptian side of the Rafah border crossing with Gaza and saw smoke rising, as a massive terrorist assault on Egyptian troops was underway some 40 kilometers (25 miles) away.
It was not immediately clear what caused the explosions or if the incident was linked to the coordinated assault on military targets in the northern Sinai Peninsula, which killed at least 50 Egyptian soldiers.
The coordinated assault, claimed by an Islamic State affiliate, is the deadliest attack in the Sinai since the 1973 Arab-Israeli war. Clashes were still ongoing through Wednesday afternoon.
Israeli and other media report that despite the airstrikes by Egyptian F-16s and the efforts of the Egyptian military, many parts of Sheikh Zuweid fell into the hands of the terrorists.
Previous reports that the town was overtaken by Islamic State were denied by the government in Cairo.
— AP contributed to this report.