The bustling city of Barcelona was the scene of a horrifying accident late Monday afternoon after two passenger buses collided, injuring over 50 people, four of whom are in critical condition, including a minor, and a pedestrian who was struck by one of the buses. 

According to reports, the accident occurred at approximately 3 p.m. local time on Monday in the Avinguida Diagonal (Central Diagonal Avenue), near the famous Sagrada Família, an extremely busy street in Barcelona. 

Authorities have indicated that one bus contained British, German, and Italian cruise ship tourists, while the second bus contained Italian students visiting the Catalan capital. 

Video footage of the bus collision is quite alarming, as the windshield and front end of the traveling bus, which rear-ended the parked bus, reveal the passenger vehicle in complete shreds. 

Deputy Mayor Albert Batlle was on the scene of the accident and reported that one passenger bus had been parked to pick up passengers at Central Diagonal Avenue when it was struck from behind by the other passenger bus, resulting in the parked bus being pushed forcefully into a tree. 

“There are four critically injured, including a minor, and three less seriously injured. The rest have suffered less serious injuries for which they are being treated in various hospitals in Barcelona,” Deputy Mayor Albert Batlle added. 

The traveling bus, according to eyewitness testimony, was moving quite fast when it ‘suddenly slammed on the breaks,’ and made impact with the parked bus, shoving it up onto the pavement where citizens were sitting on a park bench before smashing into a tree. One pedestrian walking along the pavement was said to have been struck by the bus and critically injured. 

It has not been made clear which bus contained which passengers or which bus caused the accident, but according to officials, one passenger bus contained cruise ship passengers of varying nationalities on a day trip to visit Barcelona's iconic Sagrada Família Basilica, while the second bus contained Italian students from a nearby town visiting the capital. 

A spokesman for Autocares Julia, the company operating the coach the cruise liner day trippers were on, said: “The nationalities most represented on the coach were British, German and Italians. They were on a cruise liner that had arrived in Barcelona earlier today and was due to leave in the next few hours.” 

A spokeswoman for emergency services in the northeastern region of Catalonia indicated that of the four passengers critically injured, one was a 17-year-old student, and the pedestrian caught in the collision. Reports also indicate that one passenger was trapped inside a bus and had to be extracted by emergency services. 

According to officials, adverse weather may have played a part in the collision. However, authorities and investigators are not ruling out driver negligence, possible vehicle malfunction, or any other factors that may have led to the traveling bus slamming on the brakes abruptly, prompting a full-on investigation into the cause of the crash. 

The area where the collision occurred was also congested due to the ‘opening day of the annual Mobile World Congress (MWC), the world's largest wireless technology showcase, which is set to draw around 100,000 attendees.’ 

Emergency personnel arrived at the accident en masse: fire services, police, approximately 19 ambulances, and a host of varying medical personnel were on the scene to provide aid to the passengers.