Gaza was in a state of alert on Wednesday after two explosions at police checkpoints killed three policemen. The first explosion occurred in the neighbourhood of Tal Alhawa, south-west of Gaza city, on Tuesday night and killed two police officers. Less than an hour later, a second explosion killed an officer on Beach Street, to the west of the city. Witnesses said the attacks were carried out by suicide bombers on motorbikes. Eyad Al Bozom, spokesman for Gaza’s interior ministry, promised a strong response. “We assure you that those who are behind these explosions will not escape punishment,” Mr Al Bozom said. “Our investigations are progressing and we will not stop until we reveal the full circumstances of the explosions.” Hamas spokesman Fawzy Barhom said similar incidents had happened before and accused the Palestinian Authority of involvement, but said they would wait until a full investigation had been carried out to reveal the culprit. The deadly blasts are also reminiscent of previous bloody rounds of infighting between Hamas and more radical groups that consider it not extreme enough. Hamas chief Ismail Haniyeh said that Gaza could absorb such incidents. “We are certain things will be controlled and all sides involved in these bombings will be held accountable,” he said. Immediately after the explosions, Hamas security began a campaign of arrests and put security checkpoints in place in Gaza’s main streets. The terrorist organisation Palestinian Islamic Jihad condemned the attack and assured their support for police and security services, saying they stand beside them against anything that could attack the Palestinian nation. Immediately after the first blast, Hamas’s health ministry spokesman blamed Israel, but later deleted his statement on Twitter. The Israeli military said it was unaware of any action in Gaza. The blasts came amid rising tension after Israel imposed restrictions on gas supplies to the enclave.