Mosul (Iraq) - Top Islamic State commander killed in the Islah al-Zeraie district and parts of Mosul's industrial neighborhood returned to Iraqi officials leaving around eight neighborhoods in West Mosul under the so-called Islamic State's control. Iraqi forces captured al-Maamel on Monday and then advanced to battle the Islamic State in the Islah al-Zeraie district, where IS commander Abu Ayoub al-Shami and three of his aides were killed, Iraq's Mosul Operation Command said. The Iraqi Army's 16th Division on Tuesday was fighting the Islamic State in the neighborhoods of the Hawi al-Kanisa district, half of which are under Iraqi control, Rudaw reported. Jabar Daraji, a commander for the 16th Division, said Iraqi forces found 16 Islamic State bomb manufacturing depots after capturing parts of Hawi al-Kanisa. There are eight neighborhoods left in west Mosul for forces to fully capture the city, Rudaw reported. About 350,000 people are believed to be trapped between warring sides in the densely populated areas of west Mosul under IS control. Much of the fighting is centered in west Mosul's Old City, where the Great Mosque of al-Nuri is located. Islamic State leader Abu Bakr al-Baghdadi is believed to have delivered a sermon from the mosque where he declared an Islamic State caliphate. Iraq launched its military offensive to retake western Mosul from the Islamic State, also known as Daesh, ISIL and ISIS, on Feb. 19. The offensive to retake Mosul began Oct. 17, led by Iraqi security forces and aided by the Kurdish Peshmerga, a Shiite-led militia, and the U.S.-led international coalition. Iraq fully captured east Mosul in late January. The Iraqi Interior Ministry on Monday said security forces have killed more than 3,320 IS members since the operation to capture west Mosul began.