Thailand's national police spokesman says that according to explosives experts the bomb that blew up last week in downtown Bangkok "looks like TNT," although police have not received the chemical test results.

Prawuth Thavornsiri told journalists Wednesday that it was still not clear if the bomb that killed 20 people Aug. 17 was made of TNT or C4, a plastic explosive, but based on the experience of the bomb disposal experts, "they say it looks like TNT."

Prawuth says investigators are trying to find other pieces of the bomb to analyze.

More than a week after the bombing, police appear to be no closer to tracking down suspects or determining a motive for the attack.