Despite a peace declaration signed by candidates competing for Jakarta's governor slot, a second attack on campaign headquarters took place on Tuesday.

Alex Noerdin-Nono Sampono's campaign center in Ulujami, South Jakarta was attacked by around 20 people wearing helmets and head covers on Tuesday night. Public transit driver Adi Saputra was badly injured in the attack, according to reports. The mob also destroyed campaign banners in front of the building.

"It was not random attack. It was a clear attack our post," Imam Darmadi, manager of Alex's campaign team, told Antara on Wednesday.

Imam said that in addition to reporting the incident to the police, he would also file a complaint with the Jakarta Election Supervisory Committee (Panwaslu) and General Elections Commission (KPUD).

Metro Pesanggrahan Police chief Comr. Darmawan Situmorang told Kompas.com that the Betawi Brotherhood Forum (FBR) was behind the attack – but Darmawan also said the incident was not related to the campaign "Brawls between the FBR and Pemuda Pancasila often happened [at that location]," he said.

But Imam disagreed. "If it was a brawl between groups, why bother wearing face covers," he said. "It was not a spontaneous attack, they knew it was our campaign post."

Nachrowi Ramli, the running mate of incumbent Fauzi Bowo and a retired general who heads the Betawi Consultative Body (Badan Musyawarah), where he supervises 114 organizations such as the Betawi Brotherhood Forum (FBR) and the Betawi Communications Forum (Forkabi), told people not to jump to conclusions. He suggested that the FBR might not have been behind the attack.

"This case is still under investigation," Nachrowi said. "This matter should be carefully solved so as to not create slander and conflict."

Last week, someone threw a molotov cocktail at the house of Prosperous Justice Party (PKS) candidate Hidayat Nur Wahid, and also burned the spare tire of his car. No suspects have been named or arrested int hat case.