In light of recent terrorist attacks launched against the United Kingdom, British authorities warn the latest foiled attempts could be the first of many this summer.

In response to the failed attacks, the government has raised the terror alert to “critical”—its highest level.

Since the beginning of the weekend when British authorities defused a detonator in a car filled with gasoline, nails and gas cylinders parked outside a London nightclub, police have searched over 19 locations across Britain for additional suspects, and stymied at least three other copycat attempts.

While details of the attacks have been slow to emerge, it is known that:

• Thousands of passengers were evacuated from Heathrow Airport after a suspicious package was found in one of its terminals.

• Eight people have been detained in relation to the attacks, including several doctors with Middle Eastern backgrounds. A hospital was partially evacuated after a suspicious device was found on one of the detainees taken there for treatment after he crashed into the main terminal of Scotland’s Glasgow Airport. The other suspect in the fiery crash is in critical condition.

• A man and his wife (who wore a full burqa) were arrested on the M6 highway outside of Glasgow Airport in connection to the bombings.

• All of the suspects have been reported to be Muslim and in their late 20s to early 30s.

London’s Stansted Airport was closed briefly due to the threat of repeated attacks. While authorities are unsure if the attempted plots are directly connected with al-Qaeda, none of the suspects appear to be of British descent. However, a Kurdish terror group thought to be responsible for bombings in Iraq has been connected with the three failed car bombs in London.

The situation has put UK residents on edge, leaving them to wonder what is next for their country.

The BBC reported the head of Scotland Yard’s Counter Terrorism Command confirmed, via an inside source, that by the end of the weekend three other car bombs had been discovered in London. They are thought to have been connected to the flaming jeep that rammed into the side of the Glasgow Airport, which left the area looking more like a war zone than an airport.

“There is a group of individuals out there who have the capability and the intent to carry out attacks in the UK,” he said, adding, “In our judgment it is very likely there will be further attacks.”

The recent attacks have sparked fears that a repeat of America’s 9/11 attacks could occur in the United Kingdom.

According to ABC News, a secret U.S. law enforcement report revealed that the United States had received knowledge of terror threats against “airport infrastructure and aircraft” in Glasgow and Prague, Czech Republic, two weeks prior to the actual attack.

In addition, according to an official with access to the document, the chatter is reminiscent of the type of intelligence the U.S. gathered before the September 11 attacks, in which 19 terrorists hijacked several airliners, resulting in the deaths of nearly 3,000 people.

British authorities expect more arrests as they continue their investigations, searching for clues about possible future connections to terrorist attacks.