BARCELONA - A lone police officer is believed to have shot dead four of the five terror suspects who attacked the seaside resort of Cambrils on Friday (Aug 18).

Catalan police chief Josep Lluis Trapero, who is leading investigations into the car attack that killed a woman and injured six others, told reporters: "To kill four people, even if you are a professional, is not easy."

The attack unfolded when an Audi A3 containing the five suspects ran down a number of pedestrians before crashing into a police car and overturning.

The crash left the officer's partner with a broken tibia and injured head.

According to a report in the Barcelona-based newspaper La Vanguardia, the attackers then emerged from the car brandishing knives, machetes and axes.

They also wore fake suicide vests.

Four of them were shot dead by the officer, who was armed with a rifle, while the fifth fled and stabbed a pedestrian in the face before being gunned down by another officer several hundred metres away.

Waiter Joan Marc Serra Salinas told the BBC he heard shots ring out on the Cambrils promenade and threw himself on the ground.

Cambrils mayor Cami Mendoza has praised the "speed and efficiency" of the police response.

Meanwhile, La Vanguardia reported that the officer who shot down the four attackers had been due to go on holiday this week, and is understood to be currently receiving pyschological support in the attack's aftermath.

The deadly attack came just hours after a van ploughed into pedestrians in the busy tourist area of Barcelona's Las Ramblas, killing 13 people and injuring some 100.

Spanish police have since expanded a manhunt for 22-year-old Moroccan national Younes Abouyaaqoub, without confirming reports that he was the driver.

Investigators are working furiously to unravel the terror cell of at least 12 young men - some of them teenagers - behind the twin attacks.