After a terrifying night filled with loud explosions, long lines were forming at gas stations and grocery stores were filling up as Iranians prepared for uncertain times.

Residents of Tehran weathered a night of terror and shock, reeling from explosions across the Iranian capital and from the news that senior military commanders and top-security nuclear and military bases had been attacked by Israeli fighter jets.

Long lines were forming at gas stations and grocery stores were filling up as Iranians prepared for uncertain times. As of Friday morning, the government had not given a complete tally of casualties and only said that a number of civilians had been killed, including children. Dozens were injured.

Israeli strikes targeted Natanz, the major nuclear facility near the city of Isfahan; the Parchin military base near Karaj. At least a dozen military bases, missile depots and nuclear and military research centers in multiple cities across Iran were hit.

Israel also struck residential buildings in densely populated neighborhoods of Tehran, in affluent, middle-class and working-class neighborhoods, according to witnesses, videos, photos and Iranian state media.

Iranian officials had dismissed the warning signs that Israel was planning to strike nuclear sites as propaganda and a media frenzy aimed at pressuring Tehran into concessions in talks with the United States over curbing its nuclear activities.

The government advised people to stay calm. But there was no sign of any measures to provide shelter and no guidance to the public on safety if more attacks were to come.

Fatemeh Hassani, a Tehran resident who lives in the affluent neighborhood of Pasdaran, said she and her husband and children were startled awake by an extremely loud boom, followed by another, and then another. Only when she checked her phone to see whether it was a thunderstorm did she learn that it was an attack.

Ms. Hassani said she huddled with her children away from the windows.

Across the city, Mohammad Jamali, standing on a roof near Chitgar Lake, said he could see jets approaching a military base and then a large fire and smoke billowing in the air.

Sara, a 52-year-old mother of two in Tehran, said it was a very scary night.

“We woke up with our house shaking from the explosions, and it hasn’t stopped,” said Sara, who asked to be identified by her first name only.

Mehdi, a resident in the Sadaat Abaad neighborhood, where an apartment building had collapsed, said neighbors had spilled into the streets with children in their pajamas clinging to their parents, looking dazed.

When dawn broke, the attacks had not stopped. But residents and local journalists in Tehran were in the streets anyway, taking stock of the damage.

State television reporters did live broadcasts from targeted neighborhoods. Some apartment buildings were shown half standing, and in one instance, an entire floor was blown out. In another, the roof of several buildings had pancaked and debris, shredded glass and mangled metal covered the streets.

Ali, a 42-year-old businessman who has a toddler and lives in a high-rise in northern Tehran, said in a telephone interview that he and his wife were rattled by the attacks on residential buildings, including one in their neighborhood. He was considering leaving the city for the countryside for a few days.

Some called for revenge.

At the Jamkaran mosque in the city of Qom, a crowd of government supporters gathered early Friday chanting, “Death to Israel,” and “Death to America,” according to state media.

The attack on the Natanz nuclear site closed down a major highway connecting Tehran to Isfahan, state media reported. The cities are roughly 200 miles apart.

Some Iranians feared the country was heading into an all-out war. And with air defenses taken out and military commanders killed, they wondered how the country could sustain a prolonged conflict.