The spanish newspaper describes the weapon, incorrectly IMHO as a "trabuco" (blunderbuss). I ask for a more accurate description.
I offer a translation to the news below, but I don't know if it's appropriate. Feel free to delete that text if you want.
The Salamanca Chronicle
Arrested in Aldeatejada after robbing several hotels in Ávila at blunderbuss-point
He took about 500 euros and ran away in a cab.
The Civil Guard of Salamanca arrested this Wednesday morning at a > gas station in Aldeatejada an individual who fled after carrying > out two robberies hours earlier in hotel establishments in Avila > at blunderbuss-point.
The agents believe that he could also be the author of a third > > robbery committed in another hotel in the capital of Avila on Wednesday night. At the National Police Station in Ávila on Wednesday was received the notice from several hotels alerting of having been victims of robberies by a man who carried an old muzzle gun, which led to an investigation that allowed the identification of the criminal. Meanwhile, the alleged robber, who had fled by taxi, stopped at first to refuel at a gas station in the province of Avila, where he required the employee to exchange coins for bills, at which time the worker realized that the man had a gun, something he reported to the Guardia Civil
After these communications, the police officers began working together to determine that the individual who had exchanged money at the gas station was the same one who had previously docked at the hotel establishments.
After being intercepted at the second stop at a petrol station, this time in Aldeatejada, the agents checked that the suspect was the same, and when they searched him they found the pistol and nearly 500 euros in banknotes and coins, which led to his arrest.
On the other hand, the Avila Police are investigating whether the detainee is also the author of another robbery of a hotel in the city that was committed on Wednesday afternoon. If this fact is confirmed, there would be three hotels in the capital of Avila that suffered the same type of crime.