The injured were transported to various hospitals, some by helicopter

At least four people were killed and up to 15 others critically injured when a bus transporting Chinese tourists crashed on Friday near Bryce Canyon National Park in the western US state of Utah, local authorities said.

The Utah Highway Patrol said the crash took place in the morning about seven miles from the park entrance, forcing the road to be shut as ambulances and rescue vehicles rushed to the site.

It said a total of 30 people, including the driver, were on board the bus as it headed to the famous park.

"Four have been killed 12-15 with critical injuries and 10 more with minor to serious injuries," the Highway Patrol said in a tweet.

It posted pictures of the mangled bus, with its roof partly caved in, lying on the side of the main highway leading to the park entrance.

"The bus was traveling east bound when it ran off the road and rolled into the guardrail," the Garfield County Sheriff's Office said in a Facebook message that described the crash as "horrible."

It said the injured were transported to various hospitals, some by helicopter.

China's embassy in Washington said on Twitter that it had initiated its emergency protocols and sent personnel to assist the victims.

Utah Governor Gary Hart expressed sadness over the tragedy.

"My heart sank when I heard the news that a tour bus crashed near Bryce Canyon," he said in a tweet. "I grieve with all who lost loved ones in this crash and I'm grateful for the quick work of first responders, as well as all those who are volunteering to act as translators."

Bryce Canyon is one of the most visited national parks in the US, attracting some 1.5 million tourists every year.