What we know so far about deadly Spain train crash
More than 500 passengers were on board the trains when the incident occurred in the province of Toledo, south of Madrid.
Rail operator Adif says the incident occurred between a Renfe train and another of the Iryo company, which covers the Madrid to Seville route.
The two trains collided just after 09:00 (08:00 GMT) between municipalities Mora and Orgaz, and about 140km (100 miles) south of Madrid.
The accident happened when a high-speed train travelling from Madrid to the south of the country collided with another train that was apparently stationary. The crash caused at least two carriages to fall down an embankment.
Esther Padilla, spokesperson for the government of Castilla-La Mancha region, told TVE that one of the trains - managed by the Iryo company - was carrying 146 passengers plus one baby, while the Renfe-managed train had 397 passengers on board.