(CNN) -- Egypt's interim government officially declared the Muslim Brotherhood a terrorist organization on Wednesday, blamed it for a bombing this week that killed 16 people, and announced that anyone who is a member of the group will be punished.
Hossam Issa, the interim minister of higher education and a deputy prime minister, announced the Cabinet's decision on state-run al-Masriaya television.
"The government reiterates that there will be no return to the past under any circumstances and Egypt, the state and the people, will never succumb to the terrorism of the Muslim Brotherhood whose crimes have gone far beyond all moral, religious and human limits," he said.
The government also will punish anyone giving the group financial support, Issa added.
Hundreds of supporters of the Muslim Brotherhood took to the streets in towns and cities across Egypt after the announcement.
In Alexandria, some protesters threw fireworks at authorities and set fire to police cars as young people marched through the streets chanting "Sisi is a traitor," according to the official Facebook page of the Freedom and Justice Party, the political wing of the Muslim Brotherhood. "Sisi" refers to Egypt's new leader, Gen. Abdel Fatah El Sisi.
"The terrorist coup authorities that are agents for the Zionists announced the Muslim Brotherhood as terrorists, similar to declaration made against the Palestinian resistance movement by Israel. The coup is terrorism," the group said in an online statement.
In Cairo, demonstrators holding up the four-finger sign in honor of Rabaa ("four" in Arabic) flooded the residential neighborhood of Dokki. Police violently cleared the Muslim Brotherhood's protest camp at the Rabaa al-Adawiya mosque earlier this year, killing hundreds of people in the single bloodiest day in Egypt's modern history.
Tamarod, the grass-roots political faction responsible for organizing the petition campaign that led to the overthrow of President Mohamed Morsy in July by the Egyptian military, issued a statement on its official website.
"The government's decision announcing the Brotherhood group a terrorist organization is a good step, and it came late but better to come late than never," it said.
Issa made the announcement despite the fact that Ansar Jerusalem, a jihadist group responsible for attacks in Egypt's Sinai Peninsula, has claimed responsibility for the attack on a security forces headquarters.
On Sunday, Ansar Jerusalem issued an online statement calling on army and police members to quit.
"With your staying in these institutions from evening to morning, you are incurring the anger of Allah," the statement said.
But Issa said it was an "ugly crime" perpetrated by the Brotherhood.
In addition to the 16 people killed in the early morning twin bombings, 130 people were wounded. More than 40 people remained hospitalized Wednesday. CNN first learned of the blasts from Twitter.
U.S.: Concern over current political conditions
The United States issued a strong reaction to the news that the Muslim Brotherhood was labeled as terrorists.
"We think it is essential for Egypt to have an inclusive political process; it is the best means of restoring the stability that the Egyptian people want and that is necessary to the country's economic recovery," said Jen Psaki, a spokeswoman for the U.S. State Department. "There needs to be dialogue and political participation across the political spectrum."
She repeated the United States' condemnation of the bombings, noting the Muslim Brotherhood denounced the bombing and Ansar Jerusalem, in Arabic called Ansar Bayt al-Maqdis, had taken credit for the attack. She said the United States has designated Ansar Bayt al-Maqdis as a terrorist group.
"We are concerned about the current atmosphere and its potential effects on a democratic transition in Egypt," she said.
Russia also condemned the bombings.
"Political differences, no matter how sharp they may be, should be resolved by peaceful means in the ways of a broad dialogue with the participation of leading political and social forces of the country," the Foreign Ministry said.
Upcoming vote on proposed constitution
Morsy, backed by the Muslim Brotherhood and the nation's first democratically elected president, was forced out of office in July 2013, with detractors saying he was a tyrant trying to impose conservative values.
Morsy faces charges of incitement to murder in connection with protests against his rule in December 2012. He has refused to recognize the court.
The interim Egyptian government has cracked down on the Muslim Brotherhood. The military and police have detained large numbers of Brotherhood officials and supporters since Morsy's ouster.
Several hundred people have died in clashes between pro-Morsy demonstrators and security forces since the military removed him.
The blasts come in the lead-up to Egypt's referendum on a new constitution, which will be held January 14-15.
The draft constitution would ban religious parties and put more power in the hands of the military.
Morsy has endured a series of other legal troubles. He and 132 others will face trial for escaping from prison in 2011, state media reported Saturday.
Morsy will be tried along with members of the Muslim Brotherhood and Palestinian Hamas, the Al-Ahram state newspaper reported.
He is also charged with raiding other prisons, and killing soldiers and officers in Rafah, according to the newspaper.
Morsy has been in custody since his ouster.
CNN's Saad Abedine and Hamdi Alkhshali contributed to this report.