Following a gigantic explosion in Donetsk today that shattered windows across the city and threw people of their feet, Aleksandr Zakharchenko, the prime minister of the so-called Donetsk People's Republic, officially declared the end of a ceasefire in eastern Ukraine that has more or less only existed in name.

"No more talks about ceasefire, of course we are not going to sit [at the negotiating table] with Kiev," Zakharchenko told RIA Novosit, a pro-Kremlin Russian news outlet.

At just after noon on Monday a direct hit to the Donetsk State Chemical Factory, a producer of explosives for armaments, caused a massive black mushroom of smoke to rise above the facility. An explosion shock was so powerful it buckled the metal and glass front of the city's $12 million Shakhtar Football Stadium eight miles away.

An explosion at Donetsk State Chemical Factory on Monday afternoon shattered the metal and glass front of Shakhtar Football Stadium, eight miles away.

In the city's central administration building the blast interrupted a press conference being held by the rebel leadership, hurling the minister of housing from his chair as officials and journalists scrambled to exit the building in panic.

Just a few hours later Zakharchenko announced the resumption of hostiles in a tweet: "After today's shelling of Donetsk with rockets, the ceasefire, even formally has to be considered abandoned," wrote the rebel prime minister.

The Ukrainian authorities have not yet responded to the unilateral declaration.

Signed on September 5 by representatives of the all-warring parties, the ceasefire prompted a reduction in hostilities, but fighting continued to flare in hotspots across the region.

Recent fighting has centered around Donetsk airport, where pro-Ukraine units, including patriotic volunteer battalions, have exchanged a daily barrage of grad and mortar fire with pro-Russia rebels for months.

Most civilians have now long abandoned the residential blocks in the immediate vicinity of the airport as rebels have taken over apartments as firing positions. On the other side, pro-Ukraine forces, including fighters in the nationalist paramilitary unit Right Sector, have holed up inside the airport, reportedly using underground passages to launch their assaults — a tactic that has earned them the nickname of "cyborgs."

Occasional spillovers from the fighting for the airport have resulted in civilian casualties when misfired missiles hit nearby residential districts. Most notably, a Uragan rocket strike on October 1 killed at least 10 people when it hit a school playground and public bus.

According to the United Nations, at least 331 people have been died since the ceasefire came into effect. Dmitry Kalashnikov, Director of Donetsk's morgue, told VICE News that at least 21 civilians had been killed as a result of the conflict in the past month.

At present it is unclear how the situation on the ground will be affected by the rebels announcement of the resumption of hostilities, as the period of uneasy peace has allowed a frontline to solidify, limiting the areas and unpredictability of fighting. The unilateral declaration of the end of the ceasefire — just six days before parliamentary elections scheduled to be held in Ukraine on October 26 — will be another blow to Ukraine's President Petro Poroshenko, whose self-named party has built its election campaign on a program of peace.

Earlier this week, unrest rocked the capital when a celebration of the anniversary of the formation of the "Ukrainian Insurgent Army" — a World War II partisan group that cooperated with the Nazis — descended into violence outside Kiev's parliament building. Protesters of the event hurled smoke bombs and used makeshift weapons, including chain whips, to attack riot police.

Poroshenko's Bloc holds a substantial lead in the polls, at around 26 percent, but the result of the vote is still far from clear with up to 39 percent of voters stating they are undecided which party they will back on polling day, according to an IFES poll funded by USAID.