[Updated at 10:19 p.m. ET, 4:19 a.m. in Egypt]
CNN's Ben Wedeman, who spent time at a pro-Morsy rally in Cairo on Wednesday evening, reported he spoke to one protester who said he felt demonstrators would stay there "until Mohamed Morsy is once again president of Egypt."
Wedeman recalled the exchange early Thursday after leaving the pro-Morsy rally to go to the larger gathering at Cairo's Tahrir Square, where people still were celebrating Morsy's ouster.
Wedeman said that although much focus is on the joy and excitement at Tahrir Square, "there's a significant portion of the Egyptian population -- (although) I wouldn't suggest it's a majority -- who are very upset at what has happened."
Wedeman, a CNN senior international correspondent who'd previously served as CNN's Cairo bureau chief, said it appeared the overall mood in Egypt would be different than 2011, when then-President Hosni Mubarak was deposed. In 2011, Wedeman said, Mubarak's supporters kept a low profile for months.
"There's not going to be that quiet after the storm this time around," Wedeman said.
[Updated at 10:06 p.m. ET, 4:06 a.m. in Egypt]
Get ready for an extremist backlash to Morsy's ouster, says Mohammed Ayoob, Michigan State University professor emeritus of international relations.
"The major lesson that Islamists in the Middle East are likely to learn from this episode is that they will not be allowed to exercise power no matter how many compromises they make in both the domestic and foreign policy arenas," Ayoob wrote for a CNN.com opinion piece. "This is likely to push a substantial portion of mainstream Islamists into the arms of the extremists who reject democracy and ideological compromise."
CNN's Ben Wedeman, reporting from Cairo, also said there's a danger that some members of the Muslim Brotherhood will break from the main group and "challenge (Egypt's new leaders) with violence."
They may take the attitude of "we tried to play the game, our leaders were jailed, our media have been shut down ... so we're going to destroy the system," said Wedeman, who is a CNN senior international correspondent and had previously been CNN's Cairo bureau chief.
[Updated at 9:23 p.m. ET, 3:23 a.m. in Egypt]
U.N. Secretary-General Ban Ki-moon has echoed Obama's call for a quick return to civilian rule. He appealed for "calm, nonviolence, dialogue and restraint."
[Updated at 8:24 p.m. ET, 2:24 a.m. in Egypt]
More about arrests in Egypt, according to Muslim Brotherhood spokesman Gehad El-Haddad:
-- Morsy was arrested by presidential guards at their headquarters, and is being "cut off" from the world, El-Haddad said. "They cut all his access, all his calls. No one is meeting him," the spokesman said.
-- Members of Morsy's presidential team also were arrested, El-Haddad said.
-- The head of Egypt's Freedom and Justice Party and the deputy leader of the Muslim Brotherhood also were arrested, according to El-Haddad.
-- El-Haddad told CNN he understands that hundreds of names have been put on an "arrest list," but "I can't confirm any arrests apart from these."
[Updated at 8:03 p.m. ET, 2:03 a.m. in Egypt]
Muslim Brotherhood spokesman Gehad El-Haddad just confirmed his account of Morsy's arrest to CNN by phone.
Presidential guards arrested Morsy at the guards' headquarters, El-Haddad told CNN. He described it as "house arrest." He added that Morsy's presidential team was "entirely put under arrest as well."
[Updated at 7:42 p.m. ET, 1:42 a.m. in Egypt]
Morsy is "under house arrest," as are most members of the presidential team, according to a post on Muslim Brotherhood spokesman Gehad El-Haddad's Twitter account.
[Updated at 7:27 p.m. ET, 1:27 a.m. in Egypt]