Human rights groups on Wednesday pressured Gambia to hold accountable those who ordered police to "shoot and kill" two protesters this week, warning that the excessive force brings up painful memories of the previous government.Police said on Tuesday they have arrested five officers and six civilians as they open an investigation into Monday's shooting during a protest against sand mining in Faraba Banta, about 50km south of the capital, Banjul.Human Rights Watch and Amnesty International in a joint statement said Gambia's government under President Adama Barrow must show its ability to conduct credible investigations and prosecute those responsible for the crimes.Barrow took office early last year pledging widespread reforms in the tiny West African nation after longtime President Yahya Jammeh stepped down. Jammeh's government faced numerous allegations of abuses over the years.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook"The alleged excessive use of lethal force by the security forces has conjured up painful memories from Gambia's recent past," said Sabrina Mahtani, West Africa researcher with Amnesty International. "The government's promise to investigate is a positive move."Local rights activists and other Gambians also have expressed concern."I am writing to ask that those responsible for killing the victims of the Faraba shootings be identified, arrested and brought before a court of law now," the executive secretary of the Truth, Reconciliation and Reparation Commission, Baba Galleh Jallow, wrote in an open letter to Barrow. "The job you have entrusted me with is a job I love and a job I believe can help us all build a truly just, democratic and enlightened Gambia. But it is a job I cannot do when the very things we are condemning in the past are being repeated in the present."Preliminary findings by police say six civilians and 16 police officers sustained injuries in the protests while trucks and construction equipment were vandalized and police guard posts and compounds were set ablaze, according to a dispatch seen by The Associated Press.