A bomb has exploded near the entrance of a security forces camp in the northern Egyptian city of Ismailiyah, killing one policeman and injuring at least 18 other people, including six civilians, security sources have told Al Jazeera.
Prosecutor said Thursday's blast was caused by an explosive device attached to a parked car close to the gates of the police camp.
A large amount of explosive material was used, causing a very intense explosion, Al Jazeera's correspondent in Cairo reported.
The bombing was followed by gunshots, officials said, adding that several ambulances were rushed to the site of the attack.
Police and military officials earlier said that at least 54 people had been injured in the blast, but later revised that toll downwards.
Ismailiyah and surrounding areas on the Sinai Peninsula have seen regular attacks on police and military personnel, especially since the military toppled elected President Mohamed Morsi on July 3.
The military has been conducting an extensive operation in Sinai, east of the Suez Canal, to crack down on armed groups.
|Student protests in Egypt continue despite crackdown
Earlier on Thursday, riot police fired tear gas and water cannon to disperse hundreds of pro-Islamist protesters who were demonstrating near the headquarters of the Defence Ministry in Cairo.
Egypt has been witnessing almost daily protests by supporters of Morsi since the army removed him.
Morsi's removal opened the bloodiest chapter in Egypt's modern history. Security forces have since killed hundreds of his supporters, while about 200 soldiers and policemen have died, many in attacks by armed groups in Sinai, bordering Israel and the Palestinian Gaza strip.
Students supporting Morsi have been staging daily protests for months inside and outside their universities.
Last month, Egypt's army-installed interim government issued a law that banned protests near or originating from places of worship, and made it compulsory to seek Interior Ministry permission to hold a demonstration.
Since the law was passed, hundreds of Muslim Brotherhood protesters and liberal activists have been arrested for demonstrating without police permission.