jordan pulse -
Monday morning's attacks in Kyiv were from drones - the low buzzing of these slow-moving weapons is becoming familiar across the country.
The city reverberated to the rattle of gunfire as anti-aircraft batteries frantically tried to shoot them down. Video on social media appeared to one interception.
The explosions on Monday began at about 06:30 local time (03:30 GMT). The most recent was at about 08:10 local time.
Two were close to the city centre, with sirens and car alarms heard across the area.
"The enemy can attack our cities, but it won't be able to break us," said President Zelensky, describing the attacks as "terrorising the civilian population".
What is being targeted is hard to determine. The mayor's office says residential and non-residential buildings have been hit. Railway officials say explosions were seen close to Kyiv's main station.
One Reuters journalist reported seeing fragments of a drone used in the attack that bore the words, "For Belgorod".
The Kremlin has accused Ukraine of launching missile attacks on the Russian border city of Belgorod. Ukraine has denied this.
Two gunmen - who had volunteered to fight in Ukraine - killed 11 people on Saturday at a Russian military training camp in the Belgorod region.
Recent attacks in Ukraine have targeted the country's energy infrastructure. It will be surprising if that is not the case again.
Writing on the Telegram social media site, Mr Klitschko said there were four strikes in Kyiv, although residents heard five or six explosions. He also told people to stay in air raid shelters.
But despite the warnings, the streets are far from deserted. Between the first and second set of strikes, plenty of people seemed to be going about their Monday morning business.
Mr Yermak described the kamikaze attacks as Russia's "death throes" and said Ukraine needed more air defence systems "as soon as possible".
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What are kamikaze drones?
Believed to include an Iranian-supplied weapon called the Shahed-136
These drones loiter above a target before attacking
Packed with explosives which detonate upon impact, destroying the drone
Often sent in waves and difficult to spot on radar
The US said Iran planned to send hundreds to Russia, costing just $20,000 (£17,800) each
(bbc)