Washington — Homeland Security Secretary Jeh Johnson says his department is encouraging law enforcement "to be vigilant and prepared" ahead of the July 4th holiday in the U.S. following attacks Friday in France, Tunisia and Kuwait.

Johnson says people should attend Independence Day events as planned but "remain vigilant" and report any suspicious activity. He says U.S. authorities will adjust security measures, including those unseen by the public, as necessary.

In Kuwait, a suicide bomber killed at least 25 people, while a man with suspected ties to French Islamic radicals rammed a car into a gas factory in southeastern France, triggering an explosion that injured two people. The severed head of a local businessman was left hanging at the factory's entrance. A gunman killed at least 37 people and wounded 36 in an attack on a beach resort in Tunisia Friday.

British tourists have described the horror they experienced at the beach resort in Tunisia where a gunman killed 37 people and wounded 36.

Olivia Leathley, 24, from Manchester in northwest England, told Britain's Press Association she saw one woman whose husband had been shot in the stomach in front of her. She said the woman was "dragged away by hotel reps trying to get her to safety but she was a complete mess. She was in hysterics."

Leathley said: "All she said was that he'd been shot and that he was there bleeding on the beach and he was just saying, 'I love you I love you,' and then his eyes rolled back into his head."

Debbie Horsfall from Huddersfield in northern England told the BBC the gunman had started firing on people at the sandbanks right next to her. "As he began to fire we just got up and ran straight to our hotel," she said.

White House spokesman Eric Shultz says President Barack Obama has been briefed about the three attacks in Tunisia, Kuwait and France and continues to receive updates.

He said U.S. national security staff and intelligence professionals "are in touch with their counterparts in their respective countries and continue to offer help and assistance in those countries." He said there was no immediate intelligence assessment available on the unfolding situation. "Our law enforcement officials continue to be in touch with our counterparts in France," he said.