LVIV, Ukraine -- At least five people were wounded Saturday in two barrages of strikes that damaged infrastructure including a fuel storage facility in the western Ukrainian city of Lviv, a rare attack there.

The attacks, approximately two hours apart, were an effort to "intimidate Ukrainians and diplomats from democratic countries who are in the city", Ukrainian presidential aide Andriy Yermak said on social media.

The strikes sent plumes of thick smoke over the city centre and Lviv residents out onto the streets to observe the dark clouds billowing and growing larger in gusts of wind.

Regional governor Maksym Kozytsky said the initial missile strikes within Lviv had wounded five people.

Mayor Andriy Sadovy said a fuel storage facility had caught fire after the first strikes, while the second round had inflicted "considerable damage" to a defence facility in a residential area.

In a video statement, he showed what he said was damage to a school nearby the impact site, which had had its windows blown out.

"With today's strikes the aggressor wants to say hello to President Biden who is currently in Poland." Sadovy told a press conference before it was interrupted by air raid sirens.

- Loud whistling sound -
Lviv has been largely untouched by violence, rendering it a key hub for people fleeing cities that have been under fierce Russian shelling for several weeks, such as Kharkiv in east Ukraine.

The city is just 70 kilometres (45 miles) from the border with Poland, where US President Joe Biden is currently visiting to shore up support for the fellow NATO-member, just over one month into Russia's assault on Ukraine.

Twenty-one-year-old Taras, who lives 10 kilometres (6 miles from the strikes, said he heard a loud whistling sound at around 4:30 pm (1430 GMT).

"After that, I heard other passers-by shout 'missile'. Then I heard two explosions, one with a very loud boom that echoed in the sky and the other, with a weaker sound," he said following the first attack.

Olga, 44, a bank employee who had fled to the city from Kyiv, was several kilometres from the affected site. She said she was walking when she heard two loud explosions.

"Very black smoke began to rise up. It was clear that something holding fuel had been hit. Ambulances, police cars and fire engines drove quickly towards the bombed site," she told AFP by telephone, declining to give her surname.

AFP journalists in Lviv said medical vehicles and fire engines were responding to the incident.