The world’s biggest tech firms have been named in a U.S. lawsuit brought by Congolese families who say their children were killed while mining for cobalt used to power smartphones, laptops, and electric cars. The Guardian reports that Apple, Google, Dell, Microsoft, and Tesla have all been named as defendants in the lawsuit filed on behalf of 14 parents and children from the Democratic Republic of the Congo. The companies are accused of aiding and abetting in the death and serious injury of children. The families say their children were working illegally in mines that produced battery-grade cobalt used in products made by the tech giants. The families claim children were paid as little as $2 a day, and say some were killed in tunnel collapses while others were paralyzed or suffered life-changing injuries from accidents. Cobalt is an essential component of rechargeable lithium batteries. The companies haven’t commented on the lawsuit, but a spokesperson for Glencore—the company that owns the mines— said it “does not tolerate any form of child, forced, or compulsory labor.”