• London emergency and counterterrorism units responded to an explosion in an Underground car at the Parsons Green tube station that took place around 8:20 a.m. (07:20 UTC) on Friday morning. 
• Police confirmed they are treating the explosion caused by an improvised explosive device as a "terrorist incident," though they have no details about possible suspects.

• British Prime Minister May said the official terror level would remain at "severe" and that police and that security services were all working to identify those responsible for the attack. She also called the threat of terrorism severe but surmountable.

London's Metropolitan Police reported Friday that the force's Counter Terrorism Command unit was leading the investigation looking into the morning's explosion on the London Underground system. MI5, the UK's domestic counterintelligence service, is also assisting the probe.

The police previously confirmed that they were treating the explosion as a "terrorist incident."

Assistant Commissioner Mark Rowley said that "a detonation of an improvised explosive device" had resulted in 18 injuries. The National Health Services in London confirmed that city ambulances had taken 18 individuals to the hospital and said that four more individuals had presented themselves independently, bringing the total number of hospitalized to 22.

Eyewitnesses told a DW correspondent that some injuries were caused by the blast itself while others resulted from the stampede that followed as train passengers attempted to rush out of a station normally used by fewer people.

Rowley did not confirm the ages of those injured or whether the person responsible for the bomb had been on the train. He said the city would see a heightened police presence in the upcoming days.

The explosion took place in a tube car near the Parsons Green tube station in southwest London around 8:20 a.m. (07:20 UTC). The station is on the District line. Reuters reported that the train was traveling towards the city center.

The explosion and subsequent police response brought much of the area to a standstill. Local roads were closed and residents were asked to leave the area. A Parsons Green resident who wished to remain anonymous said her daughter's school, which was located next to the station, was keeping the children inside. "I just want to see my daughter," the woman told DW.

Parsons Green residents expressed surprised that an attack had taken place near their homes, while others suggested the leafy suburb may not have been the intended target. 

"Parsons Green? It's crazy, there's nothing really round here," Natalie Williams, who works in the area, told DW. "We're not in the middle of London, we're not touristy."

The police cautioned against jumping to conclusions and tweeted, "We will release facts when we can - our info must be accurate." They asked people to avoid the area near the station and appealed to those with information or photos to get in contact with the authorities.

Social media users posted photos showing police and emergency services on the station platform assisting morning commuters. Other photos showed what looked like a white bucket in what appeared to be a Lidl grocery store bag with flames at the bottom and cables emerging around the sides.

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Emergency services respond

The London Ambulance Service quickly confirmed they had reached the scene of the incident within five minutes of the first emergency calls. None of the injured individuals were reported to be in life-threatening condition.

The London Fire Brigade also confirmed they were on the scene with six fire engines, two fire rescue units, some 50 firefighters and specialist officers.

Eyewitnesses also told Reuters that a bomb squad had arrived at Parsons Green. 

Politicians respond

A spokesperson for Prime Minister Theresa May said that she was receiving regular updates on the situation. May also tweeted her condolences for the victims and praise for London's emergency responders. 

London Mayor Khan also issued a statement stating, "Our city utterly condemns the hideous individuals who attempt to use terror to harm us and destroy our way of life." He also attended an emergency cabinet briefing with Prime Minister May at Whitehall on Friday.

Khan added that London will "never be intimated or defeated by terrorism."  

The British capital has been hit by four other terrorist attacks since the start of 2017. In June, a van ran over pedestrians on London Bridge before its drivers went on a stabbing spree. Later in the month, another vehicle rammed into pedestrians in the Finsbury Park area of north London. In May, a bombing at a concert in Manchester killed 22. Prior to that in March, another  vehicle attack took place outside Westminster. 

The Parsons Green explosion is not the first time a bomb has hit the London tube system. In July 2005, suicide bombers struck multiple Underground trains, killing over 50 people and injuring hundreds. 

A morning commute disrupted

Passengers on the train described panic and chaos erupting in the cars after a blast sent after flames swept through the tube car. Individuals present at the scene of the incident said that passengers had suffered bad facial burns and that some had hair coming off.

Susan Leslie, who lives locally, told DW that she rushed to the station after receiving a phone call from a friend who was on the affected train. “I saw people running away from the station. Some people were sitting on the curb and had burn marks,” she said.

Some of the passengers were reported to be schoolchildren, and anxiety grew among parents whose children were in a school located right next to the station. A woman whose three kids were in the neighborhood school said that school officials had told her they were liaising with police to agree on a place where parents could pick up their children. 

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The incident took place during the Friday morning when Londoners pack into the city's tube cars to get to work. Transport for London (TfL), the capital's public transport authority, said it had suspended service on the District line between the Edgeware Road and Wimbledon stations but that service remained good on the rest of the line. Various roads in the area were also closed temporarily.

TfL encouraged passengers to re-plan their commutes and announced that tube tickets would be accepted on alternative forms of public transport. 

The District line runs through much of London. The suspension of tube services on the line affected the north to south route on the western half of the city. 

Read more: London police arrest teen over item on subway

cmb/sms (AP, Reuters)