ADEN, Yemen (AP) — Five children in southwestern Yemen died after an explosive device detonated in a residential area where they were playing soccer, rights groups and eye witnesses said Saturday. The circumstances surrounding their deaths on Friday night in the Al-Hashmah subdistrict of Taiz province remain unclear. However, the Yemen Center for Human Rights and another rights group called Eye of Humanity along with Houthi-controlled Al-Masirah TV said an artillery shell was fired by militias backed by the Islah party, which is allied to the internationally recognized government in south Yemen. A spokesperson for the United Nations children's agency UNICEF told The Associated Press that they are aware of reports about the incident but can't verify the facts at the moment. Two local residents who were eyewitnesses, Ahmed al-Sharee and Khaled al-Areki, told the AP that the children were playing soccer when the explosion happened. At least three people with minor to moderate injuries were also taken to the hospital, according to the eyewitnesses. Meanwhile, Mahmoud al-Mansi, another eyewitness, said the explosive was directed from an area where forces allied with the Islah party were present. The Yemen Center for Human Rights condemned the incident in a report that included graphic photos of the children's torn bodies. Citing healthcare sources at Al-Rafai Hospital, where the victims arrived unresponsive, the group said they died from shrapnel injuries. Two of the children were 12 years old, while two others were 14 years old, according to the group. The age of the fifth child is unknown. Taiz city, the capital of the province of the same name, has been a battleground, pitting the Iran-backed Houthi militias and other militias backed by the Islah party against each other and other factions in Yemen's civil war. The city was underHouthi blockade since 2016, restricting the freedom of movement and flow of essential goods to residents, but Houthis recently opened key roads. Yemen's ruinous civil war began in 2014 when the Houthis seized the capital, Sanaa, and much of northern Yemen, forcing the internationally recognized government into exile. A coalition led by Saudi Arabia and including the United Arab Emirates intervened the following year to try to restore the government to power. The UAE-backedSouthern Transitional Councilcontrols much of the south, which has been fractured by the civil war. The council advocates for the south's secession and has its own militia forces, allied to the internationally recognized government fighting the Houthis.