Police stormed a hospital in Burundi's capital, shot and killed patients as they searched for men injured in clashes that erupted when a senior army officer announced an attempted takeover of the government, a doctor said.

Dr Antoine, a surgeon at the Bumerec hospital in Bujumbura, said Friday's attack also left some patients injured.

The attack happened on the same day President Pierre Nkurunziza, who was in neighbouring Tanzania when the attempted coup was announced, returned home. 

"We received three patients and they were here in the emergency room after that moment we see a group of policemen arrive here and they began to shoot everywhere," said Antoine, who uses only one name.

In an interview with the Reuters news agency, Antoine said: "Some patient were killed, one man was killed and the others were wounded seriously, and we do not know what they did with that."

He said hospitals in Burundi had never been attacked in any circumstances and was shocked to see his institution under fire.

Antoine said: "When there is struggle or when a group is struggling", hospitals should be treated as "neutral institution", adding, "hospitals [sic] is not for this party or that one, but hospital receives everyone, every patient."

Genesis of unrest

Burundi has been reeling from violence, which began on April 26 after the ruling party made Nkurunziza its presidential candidate. At least 15 people have been killed in the unrest.

Activists and journalists are said to be in hiding or attempting to flee the country in fear of reprisals from the state or their supporters following the abortive coup, relief agencies said.

Nkurunziza, who has not appeared in public since his return on Friday, called for an immediate end to all hostilities and urged dialogue upon his return on Friday.

"We therefore urge the immediate cessation of the demonstrations, that those who have claims do so in dialogue and consultation, not through force and revolt," Nkurunziza

The president also said any ambition to seize power by force would "bring war, poverty and other atrocities we have seen in this country".

The attempted coup triggered fierce fighting in the capital between troops backing coup leaders and those loyal to Nkurunziza.

Three army generals behind the coup attempt were arrested when they were found hiding in a house, while another senior security official was caught at the border while trying to flee to Tanzania, said presidential spokesman Gervais Abayeho.

He added that coup mastermind Godefroid Niyombare remained at large and a manhunt was under way.

Tension in capital

The city was calm but tense on Friday, with many businesses closed. Some residents who didn't support the government emerged from their homes to resume protests.

Al Jazeera's Malcolm Webb, reporting from Bujumbura, said activists were calling for fresh protests on Monday. 

"Burundi's crisis is far from over," our correspondent said.  

At least 105,000 people are said to have fled to neighbouring Tanzania, Rwanda and the DR Congo, the UNHCR said. The high numbers of refugees fleeing have also prompted concerns of a new humanitarian crisis just years after Burundi's civil war ended.

Burundi descended into civil war in 1993 following the army assassination of the country's first democratically elected President Melchior Ndadaye, a Hutu. That conflict, which opened longstanding ethnic tensions between majority Hutus and minority Tutsis, lasted until 2005.

Nkurunziza took over as president and embarked on a campaign of ethnic reconciliation and economic rehabilitation. 

Source: Al Jazeera and agencies