Hours after the car explosion incident in Liverpool, the British government on Monday raised its terror threat level from substantial to severe, the country’s second-highest terrorism threat level.

Voice of America reports that the threat level was raised after UK police labelled two major attacks including a fatal stabbing of a British lawmaker and the car explosion that occurred in the past month as terrorist incidents.

Upgrading the country’s terrorism level from substantial to severe means the country is bracing up for another terror attack that the British government considers ‘highly likely to occur.

In the aftermath of the attack, UK police arrested four men under the Terrorism Act in relation to Sunday’s car explosion.

The UK Police disclosed that the men ages 29, 26, 21 and 20 were arrested in Kensington a poverty-stricken, area of Liverpool, England.

Despite declaring the car explosion a terrorist incident, the UK police did not immediately release detailed information to back its claims.

On Sunday, Peoples Gazette reported that a car explosion outside a hospital in Liverpool injured one person and left another dead.  

Although the cause of the blast was not immediately established, counter-terrorism detectives were brought in to begin to investigate possible causes of the explosion.