(AFP) - Two explosions hit Uganda's capital Kampala on Tuesday, injuring about two dozen people in what police termed an attack on the city, the latest in a string of blasts targeting the country.

The explosions went off in the central business district of Kampala near the central police station and the entrance to parliament, police said.

"What we can say (is) this was an attack but who is responsible is a matter that is under investigation," Uganda's Assistant Inspector General of police Edward Ochom told AFP.

There was no immediate claim of responsibility.

"We have dispatched a team" to the area, Uganda Red Cross spokeswoman Irene Nakasiita told AFP, while paramedics tended to victims at Kampala's Mulago National Referral Hospital.

David Nuwamanya, the hospital's principal administrator, told AFP that 27 people, all adults, had been admitted following the explosions.

Health ministry spokesman Ainebyoona Emmanuel said on Twitter that four people were in critical condition.

"Following the unfortunate and cowardly act of terrorism, our health workers are working around the clock to save lives of those injured," he said.

The explosion near the police station shattered windows while the one near the entrance to parliament saw cars parked nearby burst into flames, Ochom said.

The twin attacks follow two blasts last month -- a bus explosion near Kampala that wounded many people and a bombing at a roadside eatery in the capital that killed one woman.

Police said last month both those attacks were connected and were carried out by the Allied Democratic Forces (ADF), an armed group active in the eastern Democratic Republic of Congo that the US has linked to the Islamic State group.

Uganda has also blamed the group for a foiled bomb attack in August on the funeral of army commander Major General Paul Lokech, nicknamed the "Lion of Mogadishu" after leading a major offensive against Al-Shabaab militants in Somalia.

- 'It was so loud' -

Salim Uhuru, mayor of Kampala Central, told AFP he was near the police station when he heard the blast and said at least one person was killed in the attack.

The authorities have not yet confirmed any fatalities.

"It was so loud. I ran towards the police station and saw one policeman I know dead on the ground. His body was scattered like mincemeat," Uhuru said.

Kyle Spencer, the executive director of Uganda's Internet Exchange Point, told AFP that the explosions had sparked panic among many people nearby.

"The road to parliament is closed off, there are people just crying, everyone else is just trying to get away from these areas," he said.

"Everybody is evacuating office buildings and the buildings are locking up and not letting anybody inside."

Parliament cancelled its Tuesday session following the attacks, asking members to avoid the area "as security forces are working hard to restore order".

The premises were put under tight security, with heavily armed soldiers securing the area as forensics officers in white overalls inspected the blast site for clues.

The US embassy in Kampala warned its citizens to steer clear of the area and monitor local news.

- Arrests -

Ugandan police last month arrested a number of ADF operatives and warned that extremists were believed to be plotting a new attack on "major installations".

The ADF, historically a Ugandan rebel group, has been accused of killing thousands of civilians in eastern DRC.

In April 2019, IS began to claim some ADF attacks on social media, presenting the group as its regional branch -- the Islamic State Central Africa Province, or ISCAP.

In March this year the United States officially linked the ADF to IS.

The ADF is considered by experts to be the bloodiest of more than 120 armed groups that roam eastern DRC, many of them a legacy of two regional wars a quarter-century ago.

The DRC's Catholic Church says the ADF has killed around 6,000 civilians since 2013, while a respected monitor, the Kivu Security Tracker (KST), blames it for more than 1,200 deaths in the Beni area alone since 2017.

© Agence France-Presse