Earlier this month, a number of terrorist attacks took a toll on the people of Barcelona - leaving at least 13 people dead and over 100 injured. 

Following the horrors of Aug. 17, the police began investigating 12 suspects - most of whom were Moroccan. Almost all of the suspected attackers are now either dead or in custody.

However, there was one man who remained at large, until now. 

This week, Moroccan police arrested a man who they believe provided the attackers with the gas canisters that were planned to be used for a larger bomb attack in the northern Spanish city. 

The arrest happened in the city of Casablanca. 

The supplier provided the cell with 120 canisters of butane gas - which police believe triggered the blast on Aug. 16 at a house in a town south of Barcelona the night before the attack, according to Reuters.

The faulty explosion killed at least two suspected members of the wider cell. 

Survivor of the Alcanar explosion, Mohamed Houli Chemlal, told a judge following the attack that the group had planned to use explosives to bomb monuments such as the city's famous Sagrada Familia church, according to Newsweek.

After the gas canisters blew up, the remaining attackers used vans to plough through the crowds at Las Ramblas area on Aug. 17, in the heart of the city of Barcelona. The attack was followed by another in the town of Cambrils. 

The so-called Islamic State terrorist group (Daesh) claimed responsibility for the attack just hours later.

On Tuesday, Spanish interior minister, Juan Ignacio Zoido, said Moroccan authorities also arrested two people in connection to the attack. 

Spanish and Moroccan authorities have been working closely together in the investigation, according to Reuters.