Britain reels after attack on Tunisia beach resort

Queen Elizabeth II said Sunday the attack on a beach resort in Tunisia has left her and her husband, Prince Philip, shocked.

The monarch said she and Philip wish to send condolences to the families of those killed in Friday's attack, which left at least 15 Britons among the 38 total dead. The toll is expected to rise.

In the statement released by Buckingham Palace on Sunday, the queen also said she sends her "deepest sympathy" to those injured and still fighting for their lives in the hospital.

She said: "Our thoughts and prayers are with those of all countries who have been affected by this terrible event."

Police have identified the suspected shooter as Seifeddine Rezgui, a young Tunisian student who was not previously known to authorities. The Islamic State of Iraq and Syria (ISIS) has taken credit for the attack.

He was shot dead by security forces but not before he claimed dozens of lives, moving from the beach to the hotel pool in search of victims. The majority were tourists from Britain, Germany and Belgium.

British police said Sunday they have mobilized more than 600 officers and staff - one of the force's largest counterterrorism deployments in recent years - to respond to the attack.

Counterterrorism police official Mark Rowley said the unusually large operation was in response to the scale of the attack, the numbers of fatalities and the international nature of the case.

Police said Sunday that nearly 400 officers have been at British airports to meet and support travelers returning from Tunisia to help identify witnesses. Senior detectives and forensic teams have also been deployed to Tunisia.

Authorities say it is the most serious attack on British people since 52 people were killed by attacks targeting London's transport network in July 2005.

Meanwhile, investigators in Tunisia said they are searching for one or more.

The Interior Ministry's spokesman said on Sunday that investigators are "sure" the attacker had help.

He said the father of the attacker, identified as Seifeddine Rezgui, and three roommates in Kairouan where he studied have been detained for questioning.

The owner of the resort hotel has insisted there was no security breakdown during an attack by a gunman with alleged ties to the extremist Islamic State group who killed at least 38 tourists in Sousse, because "unfortunately the hotel security (guards) are not armed."

Zohra Idriss of Hotel Riu Imperial Marhaba said it has five or six guards on the sandy beach.

"How can they defend themselves against someone who has a Kalashnikov and who is killing them?" Idriss said. "They tried to beat him with chairs, with the vases of flowers but it was impossible. It was all very, very quick."

Tunisia's top security official said 1,000 extra police are being deployed at tourist sites and beaches in the North African nation.

Interior Minister Mohamed Najem Gharsalli made the announcement late Saturday. He said "we don't want to make tourist establishments into barracks, that's not our goal. But we must act to guarantee the security of the tourist sector."

Thousands of tourists fled Tunisia on Saturday after the country's worst terrorist attack. Hundreds more were to leave Sunday.

The Friday attack on tourists at a beach is expected to be a huge blow to Tunisia's tourism sector, which made up nearly 15 percent of the country's gross domestic product in 2014. It also comes after 22 people were killed in March at the National Bardo Museum in Tunis.