DAMASCUS — Exuberant Syrians observed the first Friday prayers since the ouster of President Bashar Assad, gathering in the capital’s historic main mosque, its largest square and around the country to celebrate the end of half a century of authoritarian rule.

The newly installed interim prime minister delivered the sermon at the Umayyad Mosque, declaring that a new era of “freedom, dignity and justice” was dawning for Syria.

The gatherings illustrated the dramatic changes that have swept over Syria less than a week after insurgents marched into Damascus and toppled Assad. Amid the jubilation, U.S. Secretary of State Antony Blinken met with allies around the region and called for an “inclusive and non-sectarian” interim government.

Blinken arrived in Iraq on a previously unannounced stop after talks in Jordan and Turkey, which backs some of the Syrian insurgent factions. So far, U.S. officials have not talked of direct meetings with Syria’s new rulers.

The main insurgent force, Hayat Tahrir al-Sham, has worked to establish security and start a political transition after seizing Damascus early Sunday. The group has tried to reassure a public both stunned by Assad’s fall and concerned about extremist jihadis among the rebels.

Insurgent leaders say the group has broken with its extremist past, though HTS is still labeled a terrorist group by the United States and European countries.

HTS’s leader, Ahmad al-Sharaa, formerly known as Abu Mohammed al-Golani, appeared in a video message Friday congratulating “the great Syrian people for the victory of the blessed revolution.”

“I invite them to head to the squares to show their happiness without shooting bullets and scaring people,” he said. “And then after, we will work to build this country, and as I said in the beginning, we will be victorious by the help of God.”

Huge crowds, including some insurgents, packed the historic Umayyad Mosque in the capital’s old city, many waving the rebel opposition flag — with its three red stars — which has swiftly replaced the Assad-era flag with with its two green stars.

Syrian state television reported that the sermon was delivered by Mohammed al-Bashir, the interim prime minister installed by HTS this week.

The scene resonated on multiple levels. The mosque, one of the world’s oldest dating back some 1,200 years, is a beloved symbol of Syria, and sermons there like all mosque sermons across Syria were tightly controlled under Assad’s rule.

Also, in the early days of the anti-government uprising in 2011, protesters would leave Friday prayers to march in rallies against Assad before he launched a brutal crackdown that turned the uprising into a long and bloody civil war.

“I didn’t step foot in Umayyad Mosque since 2011,” because of the tight security controls around it, said one worshipper, Ibrahim al-Araby. “Since 11 or 12 years, I haven’t been this happy.”