25 dead, dozens wounded in Iraq car bombings April 29, 2013 -- Updated 1454 GMT (2254 HKT) Iraqis inspect the site of a car bomb explosion in Diwaniya, south of Baghdad, on April 29, 2013. Four of the five blasts occurred in the Shiite heartland in the southern region of Iraq Another was in Mahmoudiya, a predominantly Sunni area just south of Baghdad Baghdad (CNN) -- The longstanding bad blood between Sunnis and Shiites in Iraq boiled Monday amid another round of attacks: the killing of 25 people and wounding of dozens more in five car bombings. Four of the blasts occurred in the Shiite heartland in the southern region of Iraq. Two car bombs exploded near a busy outdoor market in Amara, killing 13 people and wounding 24 others. A bomb went off near an outdoor market in Diwaniya, killing six people and wounding 20 others. And two people died and 11 others were wounded in a bombing at a commercial area in Karbala. Another blast occurred in Mahmoudiya, a predominantly Sunni area just south of Baghdad. Four people were killed and 14 others were wounded in that attack. But the fighting has prompted fears among Iraqi leaders and international powers that the tensions between Sunnis and Shiites could escalate and bring a return of the full-blown sectarian war that raged last decade. Since the overthrow of Saddam Hussein's government last decade, Sunni Arabs have been politically marginalized and Shiites, who represent a majority of Iraqis, have emerged with more power. There have been protests for months by Sunni Arabs against the Shiite-led government and its prime minister, Nuri al-Maliki. The anger has escalated since a confrontation last week between police and protesters in Hawija. The International Crisis Group last week said that the "failure to integrate Sunni Arabs into a genuinely representative political system in Baghdad risks turning Iraq's domestic crisis into a broader regional struggle." "The most urgent task today is to tamp down the flames, and the burden for this lies above all with the government," the Belgium-based think tank said in a report. April 29, 2013 -- Updated 1338 GMT (2138 HKT) Less than two weeks after he partied with classmates in a college dorm, Dzhokhar Tsarnaev now lives in very different surroundings. April 28, 2013 -- Updated 2243 GMT (0643 HKT) CNN's Anna Coren trains to fly South Korea's new supersonic jet in the first of two special reports. April 27, 2013 -- Updated 0036 GMT (0836 HKT) CNN's Dan Rivers investigates whether Twitter is being used to help radicalize potential terrorists. April 29, 2013 -- Updated 0104 GMT (0904 HKT) The current vogue for Tibetan mastiffs in mainland China -- as much as US$750,000 has been paid prize-winning specimens -- has reached Hong Kong. April 26, 2013 -- Updated 0949 GMT (1749 HKT) Colombia's image as a country of drug cartels is replaced by a rejuvenated capital and a resilient culture. April 29, 2013 -- Updated 1336 GMT (2136 HKT) UNESCO's World Heritage Sites range from dazzling underwater ecosystems to the ruins of ancient civilizations.