Watch: Israeli PM Netanyahu: Hamas 'will pay heavy price' as violence continues
Israeli Prime Minister Benjamin Netanyahu says that Hamas "will pay a heavy price for their belligerence" as the country steps up its attacks on the Gaza Strip.
On Tuesday, the Israeli military destroyed a building used by the militant group, killing at least three militants, as Palestinian rockets continued to fall on parts of Israel.
It is the heaviest fighting between the two enemies since 2014.
Israel's prime minister Benjamin Netanyahu said in a televised address: "We are at the height of a weighty campaign.
"Hamas and Islamic Jihad paid... and will pay a very heavy price for their belligerence."
He said Israel would "continue to attack with full force", adding: "This campaign will take time".
"With determination, unity and strength, we will restore security to the citizens of Israel."
Five Israelis, including three women and a child, were killed by rocket fire on Tuesday and early on Wednesday, and dozens of people were injured.
The death toll in Gaza rose to 35 Palestinians, including 10 children, according to the health ministry, with more than 200 people wounded.
The violence began last weekend at the al-Aqsa mosque, the third-holiest site in Islam and the holiest site in Judaism.
Israeli police fired tear gas and stun grenades at Palestinians who threw stones and chairs back at them.
On Monday evening, Hamas began firing rockets from Gaza and the conflict escalated rapidly.
Hamas' exiled leader, Ismail Haniyeh, blamed Israel, saying: "It's the Israeli occupation that set Jerusalem on fire, and the flames reached Gaza."
Hamas said it had fired 210 rockets towards Tel Aviv and its suburbs, where residents had to run into air raid shelters as sirens blared and anti-rocket interceptors were seen overhead on Tuesday.
Homes in Gaza shook under the weight of the Israeli attacks, with at least 30 explosions in just minutes early on Wednesday.
UN Middle East peace envoy Tor Wennesland tweeted: "Stop the fire immediately.
"We're escalating towards a full scale war.
"Leaders on all sides have to take the responsibility of de-escalation.
"The cost of war in Gaza is devastating & is being paid by ordinary people. The UN is working with all sides to restore calm.
"Stop the violence now."
A number of factors have stoked tensions in the decades-long conflict to their worst in years, said Sky's correspondent Mark Stone earlier this week.
Palestinians were angry at an Israeli police decision, at the start of Ramadan, to barricade the seating area outside Jerusalem's Damascus Gate.
There is also the issue of Sheikh Jarrah, the East Jerusalem neighbourhood where Palestinian families are fighting a court battle with Jewish settlers who want to take their homes, claiming the land is historically theirs.
Israel captured East Jerusalem in 1967 and annexed it as their own, but most of the international community considers it to be occupied land.
Monday was also Jerusalem Day, marking the moment when Israel took control of the city.
A march by hundreds of nationalist Israelis was changed on Monday evening to avoid going through the Muslim Quarter of the Old City.