ISTANBUL — Turkey’s government, rallying behind its defiant leader, rounded up thousands of military personnel Saturday who were said to have taken part in an attempted coup, moving swiftly to reestablish control after a night of ­chaos and intrigue that left hundreds dead.

By midday, there were few signs that those who had taken part in the coup attempt were still able to challenge the government, and many officials declared the uprising a failure.

President Recep Tayyip Erdogan, speaking to hundreds of flag-waving supporters outside his home in Istanbul on Saturday evening, declared that “the strong aren’t always right, but the right are always strong.’’ He called on the United States to arrest an exile living in Pennsylvania who Erdogan claimed was behind the coup attempt.

As the insurrection unfolded Friday night, beginning with the seizing of two bridges in Istanbul by military forces, Erdogan was not heard from for hours. He finally addressed the nation from an undisclosed location, speaking on his cellphone’s FaceTime app — a dramatic scene that seemed to suggest a man on the verge of losing power. But in the early hours of Saturday, he landed in Istanbul, and steadily found his voice again, lashing out at his opponents, and one in particular.

Erdogan placed blame for the intrigue on the followers of Fethullah Gulen, a Muslim cleric living in exile in Pennsylvania, who was the president’s ally until a bitter falling out three years ago. Gulen’s followers were known to have a strong presence in Turkey’s police and judiciary, but less so in the military.

On Saturday morning, Erdogan said, referring to Gulen, “I have a message for Pennsylvania: You have engaged in enough treason against this nation. If you dare, come back to your country.’’

On Saturday evening, Erdogan, standing atop a bus outside his home, pressed this theme in a thundering message to his supporters, calling on the United States to arrest Gulen and send him back to Turkey.

Even before Erdogan’s speech, the gist of which US officials have heard before, Secretary of State John Kerry said Saturday that he would listen to any inquiries Turkey might have about the cleric.

“We fully anticipate that there will be questions raised about Gulen,’’ Kerry said.

In a statement released on the website of his group, Alliance for Shared Values, Gulen condemned the coup and supported the country’s democratic process.

“As someone who suffered under multiple military coups during the past five decades, it is especially insulting to be accused of having any link to such an attempt,’’ Gulen wrote. “I categorically deny such accusations.

Prime Minister Binali Yildirim, calling the insurrection “a stain in the history of democracy,’’ put the death toll in the clashes at 265, including civilians, progovernment forces and troops involved in the coup attempt, and said 1,440 people had been wounded. He added that 2,839 military personnel had been detained.

Disciplinary actions extended to the judicial system Saturday as an oversight body, the High Council of Judges and Prosectors, announced that 2,745 judges had been dismissed, the Anadolu Agency reported.

Later in the day, Defense Minister Fikri Isik said that state authorities were in full control of all areas in Turkey but that vigilance was required. “We have prevented the coup,’’ Isik said, “but it is too soon to say that the danger is over.’’

Noting the intensity of the violence that had erupted, Erdogan said that Turkish fighter jets had bombed tanks on the streets of Ankara, and that a military helicopter being used by the coup plotters had been shot down.

There was also a battle early Saturday at Turkey’s intelligence headquarters in Ankara, which government forces later secured, and a Turkish official said the intelligence chief, Hakan Fidan, had been taken to a secure location.

In a news briefing Saturday, Turkey’s top military officer, General Umit Dundar, the acting head of the general staff, said that “the coup attempt was rejected by the chain of command immediately.’’

“The people have taken to the streets and voiced their support for democracy,’’ he said, adding that “the nation will never forget this betrayal.’’ Dundar emphasized that only a small minority within the military, including members of the air force, a military-style police force, and armored units, had revolted.

“The army is ours,’’ Erdogan said Saturday night. “I am the chief commander.’’

Supporters of the government demonstrated in Istanbul and other cities Saturday night, chanting their disdain for the coup attempt as drivers honked their horns. “We will not fall, everything for our country,’’ some people shouted as they waved large Turkish flags.

Even as it appeared that the elected government had reestablished control, many questions remained, including who was behind the plot and what long-term damage had been done to the political system of Turkey, a NATO ally and important partner in the US fight against the Islamic State.

Much of the violence overnight related to the coup attempt was in Ankara, where different branches of the security forces fought one another over control of government buildings, including the parliament building, where several explosions were reported.