The United States "is profoundly concerned" by the reports of the "destructive earthquake" in Turkey and Syria, and "will continue to closely monitor the situation," U.S. national security adviser Jake Sullivan said in a statement late Sunday night.

"We stand ready to provide any and all needed assistance," Sullivan added, noting that U.S. President Joe Biden "has directed USAID and other federal government partners to assess U.S. response options to help those most affected."

The U.S. Geological Survey measured the quake in Turkey at magnitude of 7.8.

-ABC News' Lauren Minore

Turkey's Disaster and Emergency Management Authority (AFAD) said Monday's earthquake has killed at least 76 people in seven cities.

Meanwhile, at least 99 were killed in three Syrian cities, according to Syria's Ministry of Health.

The 7.4-magnitude quake struck the the town of Pazarcik in Turkey's southeastern Kahramanmaras province at 4:17 a.m. local time and was followed by at least 17 aftershocks, the strongest measuring 6.6.

The quake was felt intensely in several surrounding provinces, prompting AFAD to declare a "level 4 alarm," which calls for international assistance.

-ABC News' Will Gretsky

Syria's Ministry of Health said Monday that at least 42 people were killed in the northwestern cities of Aleppo, Hama and Lattakia, following a pre-dawn earthquake in neighboring Turkey.

The Syrian civil defense and medical group that operates in opposition-held areas, known as the White Helmets, has declared a state of emergency in the country's northwest

People are "trapped under the rubble," the White Helmets said, adding that it "calls on residents to evacuate residential buildings, go to open places far from buildings, and inform our teams about those trapped under the rubble."

-ABC News' Will Gretsky

The Turkish Disaster and Emergency Management Authority (AFAD) said Monday that a pre-dawn earthquake was felt in at least nine cities and was centered in the southeastern province of Kahramanmaras, about 20 miles from the major city of Gaziantep.

In Osmaniye, the city governor said 34 buildings had collapsed and at least five people had died.

Meanwhile, the governor's office in Urfa said 12 people were dead and 18 buildings had collapsed.

-ABC News' Engin Bas

Turkish President Recep Tayyip Erdogan said Tuesday that approximately 70 countries and 14 international organizations have offered aid to Turkey.

The United Nations announced a $25 million grant from the U.N. Central Emergency Response Fund to help "provide urgent life-saving assistance in the region," Stephane Dujarric, spokesperson for the secretary-general of the United Nations, said Tuesday.

The U.S. is sending two American urban search and rescue teams with 170,000 pounds of specialized tools and equipment to impacted regions in Turkey.

According to the E.U., 19 member countries, including Croatia, Estonia, France, Spain and Greece, have offered support to Turkey.

Greece sent a team of 21 rescuers, two rescue dogs and a special rescue vehicle, along with a structural engineer, five doctors and seismic planning experts in a military transport plane to Turkey, according to The Associated Press.

Israel sent the IDF Medical and a delegation from the Ministry of Defense and Ministry of Health to southern Turkey on Wednesday to create a "field hospital" and provide additional support.

According to the Russian news service Interfax, Russia sent rescue teams from the Emergency Ministry to help with cleanup efforts in Syria on Tuesday.

China will provide $6 million in aid to Turkey, Chinese Foreign Ministry spokesperson Mao Ning said. The country will also deploy "heavy urban rescue teams and medical teams" to provide "relief materials urgently needed" by the Turkish.

Mexico sent rescue teams to Turkey to assist with humanitarian recovery efforts from the earthquake, including 16 of their search and rescue dogs.

-ABC News’ Ellie Kaufman, Jordana Miller, Shannon Crawford, Christine Theodorou, Natalia Shumskaia, Anastasia Bagaeva and Emma Ogao