By Abeer Salman, Ibrahim Dahman, Khader Al Zaanoun, Tareq Al Hilou, Oren Liebermann and Tim ListerGaza City (CNN) — Israeli tanks have moved into multiple neighborhoods of Gaza City over the past 24 hours, with journalists working for CNN in the city reporting heavy shelling, explosions and the sound of gunfire. Around a million people were estimated to be in Gaza City at that time. The IDF said Tuesday that an officer was killed during fighting in Gaza City on Monday. ‘Every explosion has felt like an earthquake’Residents and reporters witnessed a heavy drone presence in the skies above Gaza City as well as Israeli attack helicopters. Allenby is the only official crossing between the West Bank and Jordan, and is the exit and entry point for West Bank Palestinians traveling abroad by land.