Demonstrators from the United Macedonia initiative, some of whom were masked, entered the building protesting the election of an ethnic Albanian Talat Xhaferi as parliamentary speaker.
Zoran Zaev, who leads the main opposition Social Democrats, was seen with blood on his face amid the chaos, while Interior Minister Agim Nuhiu told media that 10 deputies had been injured, as well as some police and journalists.
Numerous protesters were supporters of Prime Minister Nikola Gruevski, whose conservative party won elections in December but didn't get enough votes to form a government on its own. Minority Albanians, who make up a quarter of the population, led an armed rebellion in the 2000s that ended with a NATO-brokered peace agreement.
Macedonia's president Gjorge Ivanov called for unity and urged protesters to calm down and go home.
"A majority of MPs elected Talaat Xhaferi as Speaker of Parliament during a regular continued session of Parliament, witnessed by members of the public and the press".
Clashes over several hours injured 77 people, including 22 police officers and several lawmakers, authorities said. The protesters against the new Government majority are on the streets of Skopje for the past two months, opposing the formation of the Government between SDSM and three Albanian parties - DUI, Besa and the Alliance for the Albanians. "Bulgaria will continue to support Macedonia for full European Union membership and NATO", Borissov said.
"Lawmakers are primarily responsible for restoring the situation in accordance to the Constitution and laws, which were violated today", said Ivanov.
Macedonia has been without a government since the elections. Protesters exploded in anger and fought their way into the building.
"I condemn the attacks on MPs in Skopje in the strongest terms".
EU's foreign policy chief Federica Mogherini said in a statement: "The acts of violence in the Parliament are wholly unacceptable".
The US Embassy in Macedonia has condemned the violence and said in a statement the assault "is not consistent with democracy and is not an acceptable way to resolve differences". "This is the time for dialogue and not for violence", Mats Staffansson, Sweden's ambassador to Skopje, told reporters on behalf of European Union and US legations in Macedonia.
Zaev secured the cooperation of another ethnic Albanian party, giving him 69 of parliament's 120 seats.