James Bays, Al Jazeera's correspondent in Kabul, said: "We've also head of rocket attacks taking place east of here in Jalalabad, a major city in the east of Afghanistan. Ten people have been injured, four of them children, four of them women."
A suicide bomber also attacked a military post in the southern Uruzgan province, killing five people - three Afghan soldiers and two civilians.
The Taliban has said that they will attempt to disrupt the polls, and rockets have already been fired at the capital twice this month.
The Taliban have demanded that Afghans boycott the August 20 election, threatening to cut off the fingers of those who vote and vowing to attack polling stations.
Campaigning for the elections was completed on Monday, ahead of the ballot in which 17 million people are to elect a president and 420 councilors in 34 provinces.
Abdullah Abdullah is the main rival to Hamid Karzai, the incumbent, for the presidency.
Karzai has gained the support of tribal chiefs and leaders of armed groups who fought in Afghanistan's civil war.
Opinion polls are showing a lead for the president, with 45 per cent of the ballot, but not an outright majority.
Without an outright majority, Karzai would be forced into a runoff with his closest challenger, predicted to be Abdullah, his former foreign minister.
Violence has escalated in the in the run-up to the polls.
In the past week, three British soldiers were killed in the southern Helmand province, one person died in a mortar attack in Kandahar, and eight people died in a suicide bomb attack outside Nato's International Security Assistance Force headquarters.
Bays said that the head of the intelligence service has said at a press conference that in the last two weeks they had prevented 48 attempted attacks on Kabul.
"I think that shows you that they are doing everything that they can, but there is always the possibility of one of these suicide bombers getting through."
Nato-led forces have said that all offensive military operations will be suspended during the elections, with only operations considered essential to protect the population being carried out.
Afghan security personnel are under similar orders from Karzai.