The discovery of these different components led to suggestions that there could have been some accidental contamination of the samples and explosive remains, although a definitive cause of such contamination has not been established. Entire cartridges, or partial remains of cartridges, of Goma 2 ECO were recovered from the apartment in Leganés where 7 suspects of the bombings died following an explosion, the only unexploded bomb, a Renault Kangoo van found near Alcalá de Henares station on the day of the bombings, and the device that was left by the high speed railway line connecting Madrid and Seville.