On the afternoon of Aug. 17, a van plowed through pedestrians on La Rambla Street in central Barcelona, killing 13 and injuring at least 130 people, 15 of them seriously.

The driver of the van then fled on foot, killing his 14th victim while stealing his car to make his escape.

Nine hours after the Barcelona attack, five men, who are thought to have been part of the same terror cell, drove another van into pedestrians in Cambrils, killing one woman and injuring six others. All five attackers were shot and killed by Spanish police officers before they could cause further chaos.

From Nice and Paris to Berlin, and from London to Stockholm, vehicle-ramming attacks have become an all-time favorite among terrorists in Europe, due to the near impossibility of authorities to catch a whiff of such a plot before it's too late. These types of attacks alone have left over 100 people dead thus far and hundreds more injured, many of whom are left with life-altering injuries.

However, what is interesting in the scope of the broader picture regarding the Catalonia attacks in relation to Daesh is what occurred on the night before the attacks.

In Alnacar, on the night of Aug. 16, an explosion occurred which caused a building to collapse and killed two additional members of the suspected terror cell.

One of the bodies found in the rubble was that of a 40-year-old Ripoll imam known as Abdelbaki Es Satty, who is now thought to be the ringleader of the terror cell that was composed of several teenagers.

Spanish authorities believe that the explosion was accidental and occurred while the terrorists were loading explosives and gas canisters into additional vans amid plans to carry out more terror attacks in Spain.

Amidst the wreckage, investigators apparently found traces of triacetone triperoxide, or TATP, which is the trimer of acetone peroxide.

From Paris to Verviers, Brussels and Manchester, TATP has been used in nearly all of the terror attacks in Europe that have been perpetrated with explosive materials. From the U.K. to Russia, there have also been several reports of intelligence agencies thwarting terror attacks related to TATP.

All of the TATP-related attacks on the continent, as well as many others worldwide, have been claimed by Daesh.

Although it's an unstable explosive substance, it is relatively easy to manufacture with some very basic skills in chemistry. The ingredients, such as acetone, hydrogen peroxide and sulfuric acid, can all be found in hardware stores, household detergents and batteries.

The lab equipment needed to make the bomb is very basic as well, and the actual recipe and dosage of each substance is widely available online and presumably in the various online publications made by Daesh, too. Their magazine has been downloaded tens of thousands of times in the U.K. alone.

While the Catalonia attacks have been claimed by Daesh, it is not yet official whether the imam, or any other terrorist, was actually in contact with the group. However, Daesh-related material was recovered from the destroyed building in Alcanar.